THE  JOHNS  HOPKINS  UNIVERSITY 
OOL  OF  HYGIENE  AND  PUBLIC  HEALTH 


DIAGNOSIS  OF  PROTOZOA 

AND 

WORMS  PARASITIC  IN  MAN 


BY 

ROBERT  W.  HEGNER 

Associate  Professor  of  Protozoology 

AND 

WILLIAM  W.  CORT 
Associate  Professor  of  Helminthology 

DEPARTMENT  OP  MEDICAL  ZOOLOGY 

SCHOOL  OP  HYGIENE  AND  PUBLIC  HEALTH 

THE  JOHNS  HOPKINS  UNIVERSITY 


1921 

BALTIMORE,  MARYLAND 
U.  S. A. 


X 


THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

PRESENTED  BY 

PROF.  CHARLES  A.  KOFOID  AND 
MRS.  PRUDENCE  W.  KOFOID 


THE  JOHNS  HOPKINS  UNIVERSITY 
SCHOOL  OF  HYGIENE  AND  PUBLIC  HEALTH 

DIAGNOSIS  OF  PROTOZOA 

AND 

WORMS  PARASITIC  IN  MAN 


BY 

ROBERT  W.  HEGNER 

Associate  Professor  of  Protozoology 

AND 

WILLIAM  W.  CORT 

Associate  Professor  of  Helminthology 

DEPARTMENT  OF  MEDICAL  ZOOLOGY 

SCHOOL  OF  HYGIENE  AND  PUBLIC  HEALTH 

THE  JOHNS  HOPKINS  UNIVERSITY 


1921 

BALTIMORE,  MARYLAND 
U.  S.  A. 


COMPOSED  AND  PRINTED  AT  THE 

WAVERLY  PRESS 

BY  THE  WILLIAMS  &  WILKINS  COMPANY 

BALTIMORE,  MD.,  U.  S.  A. 


PREFACE* 

' 

This  bulletin  has  been  prepared  for  the  use  of  physicians 
and  public  health  workers  who  are  called  upon  to -diagnose 
diseases  caused  by  Protozoa  and  worms.  No  attempt  has 
been  made  to  include  in  the  keys  and  descriptions  all  of  the 
species  that  are  now  known.  On  the  contrary,  species  that 
have  been  recorded  only  once  or  a  very  few  times  have  been 
purposely  omitted  to  avoid  confusion. 

The  information  and  figures  contained  in  this  bulletin 
have  been  selected  from  original  articles  in  periodicals,  and 
from  reference  and  text  books  wherever  available.  Credit 
for  the  use  of  figures  is  given  in  every  case  in  the  descriptions 
of  the  figures.  A  few  of  the  more  important  books  and 
articles  relating  to  the  parasites  described  are  listed  at  the 
end  of  the  account  of  each  group.  Other  lists  will  be  found 
in  the  bibliographies  contained  in  most  of  these  books  and 
articles.  So  far  as  possible  we  have  verified  statements 
regarding  the  organisms  described,  but  errors  are  almost 
certain  to  creep  into  such  a  compilation,  and  we  will  welcome 
corrections.  We  will  also  be  glad  to  accept  any  suggestions 
for  the  improvement  of  the  bulletin  which  may  be  incor- 
porated in  a  second  edition  if  called  for. 

The  methods  employed  by  various  workers  for  the  diag- 
nosis of  parasitic  Protozoa  and  worms  are  very  numerous 
and  only  a  few  could  be  described  in  this  bulletin.  These 
have  been  selected  on  the  basis  of  simplicity  and  effective- 
ness. It  seems  to  us  desirable  that  methods  applicable  to 
field  conditions  and  requiring x  the  minimum  of  apparatus 
and  reagents  should  be  emphasized.  Modifications  of  these 
methods  may  be  devised  to  fit  the  circumstances  encountered 
in  the  field. 

*  The  publication  of  this  bulletin  was  made  possible  by  a  grant 
from  the  International  Health  Board. 

3 


GENERAL  LITERATURE  LIST 

This  general  list  contains  titles  of  only  a  few  books  and 
periodicals  selected  on  the  basis  of  helpfulness  and  accessi- 
bility. Special  lists  will  be  found  at  the  end  of  each  section 
of  the  bulletin. 

GENERAL  REFERENCE  BOOKS  ON  ANIMAL  PARASITES  OF  MAN 

» 

BRUMPT,    E.:  Precis    de    Parasitologie.    2    ed.    1011    pp.    Paris, 

1913. 

CASTELLANI,  H.,  AND  CHALMERS,  H.  J. :  Manual  of  Tropical  Medi- 
cine.   3  ed.    2436  pp.    London,  1919. 
CHANDLER,  A.  C.:  Animal  Parasites  and  Human  Disease.    570  pp. 

New  York,  1918. 
FANTHAM,  H.  B.,  STEPHENS,  J.  W.  W.,  AND  THEOBALD,  J.  F.:  Animal 

Parasites  of  Man.    900  pp.     New  York,  1916. 
MANSON,  SIR  PATRICK:  Tropical  Diseases.    5  ed.    937pp.    London, 

1914. 

MENSE:  Handbuch  der  Tropenkrankheiten.    2  Aufl.    1915. 
NEUMAN,  R.  O.,  AND  MAYER,  M.:  Atlas  und  Lehrbuch  wichtiger 

tierischer    Parasiten    und    ihrer    Uebertrager.     580     pp. 

Munich,  1914. 
STITT,   E.  R.:  Practical  Bacteriology.    Blood  Work  and  Animal 

Parasitology.    5  ed.    559  pp. 

GENERAL  PERIODICALS  ON  ANIMAL  PARASITES  OF  MAN 

Tropical  Diseases  Bulletin.    Vol.  1,  1912,  London. 

Parasitology.    Vol.  1,  1908,  Cambridge. 

Annals  of  Tropical  Medicine  and  Parasitology.  Vol.  1, 1907,  Liver- 
pool. 

Journal  of  Parasitology.    Vol.  1,  1914,  Urbana,  Illinois. 

Centralblatt  fur  Bakteriologie,  Parasitenkunde,  und  Infections- 
krankheiten.  Vol.  1,  Jena,  1887. 

Memorias  do  Institute  Oswaldo  Cruz.    Vol.  1, 1909,  Rio  de  Janeiro. 

Bulletin  de  la  Socie^e*  de  Pathologic  Exotique.     Vol.  1,  1907,  Paris. 

Archives  de  Parasitologie.    Vol,  1,  1898,  Paris. 

Archiv  fur  Schiffs-uncJ  Tropen-Hygiene,    Vol.  1,  1897,  Leipzig. 


LITERATURE    LIST  5 

Journal  of  Tropical  Medicine  and  Hygiene.     Vol.  1,  1898,  London. 
Transactions  of  the  Society  of  Tropical  Medicine  and  Hygiene. 

Vol.  1,  1907,  London. 

Indian  Journal  of  Medical  Research.     Vol.  1,  1913. 
Philippine  Journal  of  Science,  Series  B.     Manila,  1906. 

GENERAL  BOOKS  AND  PERIODICALS  ON  PROTOZOOLOGY 

CALKINS,  G.  N. :  Protozoology.    349  pp.    Philadelphia,  1909. 

DOFLEIN,  F. :  Lehrbuch  der  Protozoenkunde.    4  ed.     Jena,  1917. 

HARTMANN,  M.,  AND  SCHILLING,  C.:  Die  Pathogenen  Protozoen. 
462  pp.  Berlin,  1917. 

MINCHIN,  E.  A.:  Introduction  to  the  Study  of  the  Protozoa.  520 
pp.  London,  1917. 

PROWAZEK,  S.  V.,  AND  OTHERS:  Handbuch  der  Pathogenen  Proto- 
zoen. Leipzig,  1912-14. 

ROBERT,  A.:  Protozoaires.     Paris,  1914. 

Archiv  fur  Protistenkunde.     Vol.  1-39.     1902-1919.     Jena. 


TABLE  OF  CONTENTS 

Preface. .  


PART  1.    PROTOZOA  PARASITIC  IN  MAN 

1.  Introduction  to  the  Protozoa 11 

2.  Blood  Inhabiting  Protozoa  of  Man 11 

A.  Organisms  that  cause  malaria  in  man.  1.  Classifica- 
tion. 2.  Life  history.  3.  Distinguishing  features  of 
the  three  species  of  Plasmodium  occurring  in  man. 
4.  Methods  of  making  films  for  the  diagnosis  of  ma- 
laria. Special  literature  on  malaria 11 

'  B.  Organisms  that  cause  trypanosomiasis  (sleeping  sick- 
ness and  Chagas'  disease)  in  man.  1.  Classification. 
2.  Description  of  species.  3.  Methods  of  diagnosis. 
Special  literature  on  trypanosomiasis 18 

C.  Organisms  that  cause  leishmaniasis  in  man.  1.  Class- 
ification. 2.  Description  of  species.  3.  Methods  of 
diagnosis.  Special  literature  on  leishmaniasis 19 

3.  Intestinal  Protozoa  of  Man 21 

A.  Methods  of  fecal  diagnosis  of  intestinal  protozoa.     1. 

Donaldson's  iodin-eosin  smear  method.  2.  Cropper 
and  Row's  concentration  method.  3.  Schaudinn's 
^alcoholic  sublimate  iron-haematoxylin  method.  Spe- 
cial literature  on  methods  of  diagnosis  of  intestinal 
protozoa 21 

B.  Intestinal  Entamoebae  of  man.     1.  Classification.    2. 

Species.  3.  Distinguishing  features  (a)  of  motile 
stages  and  (b)  of  cysts.  4.  Distinguishing  features 
of  cysts  of  intestinal  amoebae  of  man;  (a)  Entamoeba 
histolytica.  (b)  Entamoeba  coli.  (c)  Endolimax  nana. 
Special  literature  on  Entamoebae 23 

C.  Intestinal  Flagellates    of    man.     1.   Classification.    2. 

Description  of  species,  (a)  Trichomonas  hominis.  (b) 
Chilomastix  mesnili.  3.  Methods  of  diagnosis.  Spe- 
cial literature  on  intestinal  flagellates 31 

D.  Intestinal  Coccidia  of  man.    1.  Classification.    2.  De- 

scription of  species,  (a)  Isosporahominis.  (b)  Eimeria 
wenyoni.  3.  Methods  of  diagnosis.  Special  litera- 
ture on  Coccidia 34 


8  TABLE    OF   CONTENTS 

E.  Intestinal  Ciliates  of  man.     1.  Classification.    2.  De- 

scription of  species,  (a)  Balantidium  coli.  (b)  Nycto- 
therus.  3.  Methods  of  diagnosis 36 

F.  Some  vegetable  organisms  in  human  feces.     1.  Blasto- 

cystis  hominis.    2.  Intestinal  yeasts 37 

PART  II.  WORMS  PARASITIC  IN  MAN 

1.  Introduction 38 

2.  Diagnosis  of  diseases  caused  by  parasitic  worms 38 

3.  Key  for  diagnosis  of  human  helminths 42 

4.  Trematoda 49 

A.  Definition 49 

B.  Systematic  position  of  human  forms 50 

C.  Intestinal  trematodes.     1.  Fasciolopsis   buskii.    2.  He- 

terophyes  heterophyes.    3.  Metagonimus  yokogawai  ...     50 

D.  Liver  flukes.     1.  Genus  Clonorchis.    2.  Opisthorchisfe- 

lineus 52 

E.  The  lung  fluke.    Paragonimus  westermanii 53 

F.  Blood  flukes.    Genus  Schistosoma 57 

5.  Cestoda 57 

A.  Definition 57 

B.  Order  Pseudophyllidea.    Diphyllobothrium   latum    (Di- 

bothriocephalus  latus) 58 

C.  Order    Cyclophyllidea.      1.  Genus    Hymenolepis.      2. 

Genus  Taenia.  3.  Echinococcus  granulosus  (Taenia 
echinococcus) 59 

6.  Nematoda 62 

A.  Definiti6n 62 

B.  Family  Angiostomidae.    Strongyloides  stercoralis 62 

C.  Family  Dracunculidae.    Dracunculus  medinensis 63 

D.  Family  Filaridae.     1.  Filaria  bancrofti.    2.  Filaria  oz- 

zardi  (Filaria  demarquayi).  3.  Loa  loa  (Filaria  loo). 
4.  Acanthocheilonema  perstans  (Filaria  perstans).  5. 
Dirofilaria  magalhaesi.  6.  Onchocerca  volvulus 64 

E.  Family  Trichinellidae.     1.  Trichuris  trichiura.    2.  Tri- 

chinella  spiralis 67 

F.  Family  Metastrongylidae 68 

G.  Family  Trichostrongylidae.     Trichostrongylus  orientalis   68 


TABLE    OF   CONTENTS  9 

H.  Family     Ancylostomidae.     1.  Sub-family     Ancylosto- 
minae.       (Ancylostoma     duodenale).      2.  Sub-family 

Bunostominae.     (Necator  americanus) 69 

1.  Family  Strongylidae 70 

J.  Family  Ascaridae.    A scaris  lumbricoides 71 

K.  Family  Oxyuridae.    Enterobius  vermicularis 72 


PART  I.  PROTOZOA  PARASITIC  IN  MAN 

ROBERT  W.  HEGNER 
1.  INTRODUCTION  TO  THE  PROTOZOA 

The  Protozoa  may  be  defined  as  unicellular  animal  organ- 
isms usually  microscopic  in  size,  but  nevertheless  exhibiting 
many  activities  similar  to  those  of  the  higher  animals, 
though  in  a  simpler  form.  They  are  generally  separated 
into  four  classes  according  to  the  presence  or  absence  of 
locomotor  organs  and  the  character  of  these  when  present. 
The  class  Sporozoa  contains  only  parasitic  species,  but  the 
other  three  classes  comprise  both  free  living  and  parasitic 
forms.  Species  parasitic  in  man  occur  in  all  four  classes. 
The  following  is  a  brief  classification  of  the  Protozoa  with 
examples  of  human  parasites. 

Class  1.  Rhizopoda.  With  pseudopodia.  Entamoeba  hi8tolytica) 
E.  coli,  Endolimax  nana. 

Class  2.  Mastigophora.  With  flagella.  Giardia  intestinalis, 
Trichomonas  hominis,  Trypanosomagambiense,  Leishmania  donovani. 

Class  3.  Sporozoa.  Without  locomotor  organs  in  adult  stage: 
sporulation  occurs.  Plasmodium  vivax,  Isospora  hominis. 

Class  4.  Infusoria.    With  cilia.    Balantidium  coli. 

2.  BLOOD  INHABITING  PROTOZOA  OF  MAN 
A.  Organisms  that  Cause  Malaria  in  Man 

1.  Classification.  The  organisms  that  cause  malaria  in 
man  belong  to  the  class  Sporozoa,  subclass  Telosporidia, 
order  Haemosporidia  and  family  Plasmodidae. 

The  members  of  the  class  Sporozoa  are  parasitic  Protozoa 
without  locomotor  organs  and  are  further  characterized  by 
the  method  of  reproduction  known  as  sporulation.  In  the 
subclass  Telosporidia  the  vegetative  (trophic)  stage  precedes 

11 


12  MALARIA 

and  is  separate  from  the  spomlation  stage.  The  members 
of  the  order  Haemosporidia  are  intracellular  in  the  tropho- 
zoite  stage,  have  no  resistant  spores  and  undergo  an  alter- 
nation of  schizogony  in  a  vertebrate  and  sporogony  in  a 
blood  sucking  invertebrate  (e.g.  mosquito).  To  the  family 
Plasmodidae  belong  the  genera  Haemocystidium  which  occurs 
in  reptiles,  and  Plasmodium  which  includes  the  malarial 
organisms.  Three  species  of  Plasmodium  are  known  from 
man,  (1)  P.  vivax,  which  causes  tertian  malaria,  (2)  P. 
malariae,  which  causes  quartan  malaria,  and  (3)  P.  fal- 
ciparum,  which  causes  aestivo-autumnal  malaria.  Malarial 
organisms  also  inhabit  lower  animals,  such  as  P.  danilewskyi 
in  birds,  P.  kochi  in  chimpanzees,  P.  bovis  in  cattle,  P.  canis 
in  dogs,  P.  equi  in  horses  and  P.  diploglossi  in  lizards.  In 
the  accompanying  table  the  distinguishing  features  of  the 
three  species  of  Plasmodium  occurring  in  man  are  contrasted 
as  an  aid  in  identification. 

2.  Life  history  (Plate  I).  Certain  species  of  mosquitoes 
of  the  xgenus  Anopheles  are  the  transmitting  agents  of  the 
malarial  organisms  of  man.  Infective  mosquitoes  carry  the 
organisms  in  their  salivary  glands;  from  here  they  pass  into 
the  blood  of  any  animal  the  mosquito  bites.  The  stages  in 
the  life  history  of  the  tertian  parasite,  Plasmodium  vivax 
are  briefly  as  follows : 

a.  Sporozoite:  a  falciform  body  about  14  microns  long, 
present  in  infective  mosquitoes;  the  stage  that  is  inoculated 
into  man.     The  sporozoites  enter  red  blood  cells,  usually 
only  one  to  a  cell,  where  they  become  amoeboid  in  shape. 

b.  Trophozoite:  the  first  stage  in  the  red  blood  cell,  at 
first  ring  shaped,  later  amoeboid,  and  finally  circular  or 
oval    in    outline.     The    trophozoites    develop    into    either 
schizonts  or  gametocytes. 

c.  Schizont:  a  stage  that  develops  from  a  trophozoite, 
and  undergoes  segmentation  into  from  15  to  20  spores  known 
as  merozoites. 


PLATE  I 


PLATE  I 

LIFE-CYCLE  OF  THE  TERTIAN  MALARIAL  ORGANISM,   Plasmodium 

vivax 

The  stages  above  the  dotted  line  occur  in  the  peripheral  blood  of 
man,  whereas  those  below  are  found  only  in  the  mosquito. 

1.  Sporozoite.  2.  Trophozoite,  in  red  cell.  3.  Full-grown  schi- 
zont.  4.  Schizont  with  chromatin  in  several  masses.  5.  Seg- 
mentation stage.  6a.  Male  gametocyte.  6b.  Female  gametocyte. 
7a.  Exflagellation  of  male  gametocyte — formation  of  microgametes. 
7b.  Female  gametocyte  extruding  chromatin  from  nucleus.  8. 
Fertilization  of  macrogamete  by  microgamete.  9.  Ookinete.  10. 
Young  oocyst.  11.  Oocyst  with  sporoblasts  forming.  12.  Ripe 
oocyst  discharging  sporozoites. 

13 


PLATE  II 


B 


\    '    - 


PLATE  II 
BLOOD  INHABITING  PROTOZOA  OF  MAN 

A.  1  to  4.    Plnsmodium  vivax. 

B.  1  to  4.    P.  malariae. 

C.  1  to  4.    P.  falciparum.     (1)  Young  trophozoite.     (2)  Older 
trophozoite.     (3)  Presegmentation  stage.     (4)  Gametocyte. 

D.  1  to  3.     Trypanosoma  gambiense.     (1)  Long  form.     (2)  Inter- 
mediate form.     (3)  Short  form.     (After  Castellani  and  Chalmers.) 

E.  Trypanosoma  cruzi.     (After  Brumpt.) 

F.  1.  Leishmania  donovani.     (After  Brumpt.) 
•     F.  2.  L.  tropica.     (After  Row.) 

Figures  D,  E  and  F  are  magnified  1400  diameters. 

14 


MALARIA  15 

d.  Merozoite:  minute  amoeboid  spores  that  are  liberated 
from  the  red  blood  cells  containing  segmented  schizonts, 
and  attack  new  red  cells. 

e.  Gametocyte:  a  stage  that  may  develop  from  a  tropho- 
zoite.     It  does  not  segment  but  remains  in  the  blood  of 
man  until  it  degenerates  or  is  sucked  up  by  a  mosquito.    In 
the  stomach  of  the  mosquito  certain  gametocytes  change  into 
macrogametes;  others  produce  filamentous  microgametes. 

/.  Fertilization:  a  stage  that  occurs  in  the  stomach  of  the 
mosquito  during  which  a  microgarnete  fuses  with  a  macro- 
gamete.  The  resultant  cell  becomes  a  motile,  vermiform 
stage  known  as  an  ookinete.  The  ookinete  penetrates  the 
wall  of  the  stomach,  becomes  an  oocyst  and  causes  the 
formation  of  a  swelling  projecting  into  the  body  cavity. 

g.  Oocyst:  a  spherical  body  that  develops  from  the 
ookinete.  It  produces  within  it  hundreds  of  sporozoites 
which  break  out  into  the  body  cavity.  Many  of  these 
reach  the  salivary  glands  of  the  mosquito  where  they  remain 
until  transferred  to  another  animal  when  the  mosquito  bites. 

The  periods  occupied  by  the  various  stages  are  as  follows : 
(a)  Growth  from  sporozoite  or  merozoite  to  full  grown 
schizont — 30  hours;  (b)  segmentation — 18  hours;  (c)  devel- 
opment in  mosquito  from  gametocytes  to  oocysts — 40  hours; 
(d)  from  oocysts  to  sporozoites — 4  or  5  days.  The  asexual 
cycle  of  Plasmodium  vivax  in  man  is  48  hours.  The  mos- 
quitoes become  infective  about  8  days  after  they  suck  up 
gametocytes.  The  principal  differences  between  Plasmo- 
dium vivax  and  P.  malariae  and  P.  falciparum  are  indicated 
in  the  accompanying  table  (3) . 

4.  Methods  of  making,  films  for  the  diagnosis  of  malaria. 
1.  Thin  films,  a.  Equipment:  Clean  glass  slides;  small  bot- 
tle of  alcohol;  small  package  absorbent  cotton;  Hagedorn 
needle  fastened  in  cork  of  small  vial  and  extending  down 
into  alcohol. 


16 


MALARIA 


O    c3 

a 

&a 

GD 

fll 

^0 

P.  FALCIPARUM 

stivo-autumnal; 
idian;  subtertian; 
ignant  tertian 
48  hours 

segmenting  stag< 

B 

0 

a 

0 

o  ^_ 

rt     O 

S  ri 

;ive  amoeboid 

*3 

a 
g 

a 

o3 
43 

•4-3 

* 

« 

•tially  decolorizec 

3 

0 

-o 

W3 

"j-l 
o 

^ 
^3 

if 

•§  3 

O 

o> 

45 

1 

b 
0 
h 

cS 

1 

sscentic 

$•* 

o 
* 

O 

0 

< 

CO 

o3 

PH 

s 

1  " 

0  Jt 

M 

w 

o 

42 

H 

O 

_g 

3 

*3 

3  S 

*& 

C2 

"o 

rH 

^    0 

^S 

1 

£ 

0) 

•s 

g 

C- 

-4-5 

3 

'H. 

rt 

c 

a 

'^        K>^ 

0 

j 

i 

03 

1 

a 

b^43 

"S 

^ 

*03      0) 

d 

S 

^H        ^£ 

O 

w 

pi 

'pj"g«             03 

o 

§ 

*» 

^  ^ 

5 

bO 

1 

"S    "^            O 

§  °     g2 

5 

P 

"02 

1 

Norma 

| 

Q 

0 
G 
0 

g"  ^ 

'5    ° 

g  > 

O 

o3   <N 

^      1™"^ 

0) 

0 

1 

a 

CO 

3 

"^3 

Ij 

43 
o 

"3 

a 

c 

H 

g 

a§ 
•3  "° 

.2 

0> 

'o 

1 

h 

0 

a 

a 

i 

3 

O 

03 

(N 

J-, 

. 

J     0 

a 

o 

o 

a 

43 

o 

cc 

*§ 

O 

^ 

^"^     OJ               02 

o 

§1    s 
«.§    £ 
1  M    ^ 

3 

s 

1 

0 

1 

1 

O) 

S  chuff  n 

t| 
J  s 

CO 

1? 

5S 

1—  I 

o 

o 

a 

CO 

i_l 

^_, 

TJ 

b£) 

T3 

T3 

i 

I 

0) 

> 
^            "c 

*S          ej  -2 
0            &c  ^ 

>>                   0)     ° 

H            h3 

1 

1 

40 

CO 

Parasites  in  infecte' 
red  cells 

Movement  of  youn 

trophozoite 
Size  of  infected  re 
cells 

I 

o 

o 

o   *"* 

o 

Granules  in  infecte 

« 

^  15 

o    S 

<D 

1| 

PH 

Shape  of  schizont 
Number  of  mero 

zoites 
Arrangement  of  mei 
ozoites 

Gametocytes 

r-I                     (N 

CO 

<* 

10 

(6 

^ 

CO 

O5 

O   I-H" 
i—  i   t^i 

CQ 

CO 

MALARIA  17 

6.  Obtaining  blood:  Clean  ear  lobe  or  end  of  finger  with 
alcohol.  Puncture  with  needle.  One  drop  of  blood  is 
mounted  one  half  inch  from  the  end  of  the  slide.  Place 
the  end  of  another  slide  near  the  drop  of  blood  at  an  angle 
of  30  degrees  to  45  degrees  with  the  shorter  end  of  the  slide. 
Draw  this  slide  along  until  it  touches  the  drop.  When  the 
blood  has  spread  along  the  edge  push  the  slide  fairly  rapidly 
toward  the  other  end.  A  thin  film  -will  result  covering  about 
one-half  of  the  slide.  Allow  the  film  to  dry,  then  write 
data  directly  in  it  with  a  lead  pencil. 

c.  Fixing  and  staining.  (1)  Wright's  stain:  Cover  film 
with  a  few  drops  of  the  stain  and  allow  to  remain  one  minute. 
Add  double  the  volume  of  distilled  water.  After  five  min- 
utes, wash,  and  dry  in  air.  The  cytoplasm  of  the  parasite 
stains  blue  and  the  chromatin  red.  The  pigment  remains 
brown,  unstained. 

(2)  Irishman's  stain:    Proceed  as  with  Wright's  stain. 
Vary  length  of  periods  if  necessary.     The  results  are  similar 
to  those  obtained  by  the  use  of  Wright's  stain. 

(3)  Giemsa's  stain:  Fix  in  absolute  methyl  alcohol  for 
5  minutes,  wash  gently.     Stain  in  one  part  Giemsa  plus 
ten  parts  distilled  water  for  ten  minutes.     Wash.     Dry. 
The  results  are  similar  to  those  obtained  by  the  use  of 
Wright's  or  Leishman's  stains. 

2.  Thick  films,     a.  Equipment:  Same  as  for  thin  films. 

6.  Obtaining  blood:  Same  as  for  thin  films,  except  several 
drops  are  obtained  near  center  of  slide  and  spread  with  the 
needle  over  an  area  of  one-half  to  three-fourths  of  an  inch. 

c.  Fixing  and  staining:  Fix  and  decolorize  in  95  per  cent 
alcohol  plus  2  per  cent  HC1  for  one-half  hour.  Wash  in 
running  tap  water  a  few  minutes.  Stain  as  with  thin  films. 
In  these  preparations  more  blood  cells  are  present  per  unit 
area  and  hence  the  presence  of  parasites  is  more  easily 
determined. 


18  TRYPANOSOMIASIS 

Special  Literature  on  Malaria 

ASCOLI,  V.:  La  Malaria.     1127  pp.     Torino,  1915. 

CRAIG,  C.  F.:  The  Malarial  Fevers,  Haemoglobinuric  Fever  and  the 

Blood  Protozoa  of  Man.    477  pp.     New  York,  1909. 
HINDLE,   E.:  Flies  in  Relation  to  Disease.    Blood-sucking  Flies. 

398  pp.    Cambridge,  1914. 
JAMES,   S.  P.:  Malaria  at  Home  and  Abroad.    234  pp.     London, 

1920. 
Ross,  R.:  The  Prevention"  of  Malaria.    2d  ed.    711pp.    London, 

1911. 
ZIEMAN,    H.:  Die   Malaria.     In   Mense's   Handbuch   der    Tropen- 

krankheiten.     Bd.  5,  ed.  2,  602  pp.     Leipzig,  1918. 

B.  Organisms  that  Cause  Trypanosomiasis  (Sleeping  Sickness 
and  Chagas*  Disease)  in  Man 

1.  Classification.     These  diseases  are   caused  by  blood- 
inhabiting  Protozoa  known  as  trypanosomes.     They  belong 
to  the  class  Mastigophora  whose  members  are  characterized 
by  the  presence  of  one  or  more  permanent  whip-like  loco- 
motor  organs  called  flagella.     The  flagellates  comprise  both 
free-living   and   parasitic   species.     For   the   sake   of   con- 
venience the  flagellates  that  spend  part  of  their  life  cycle 
jn  the  blood  of  vertebrates  and  the  other  part  in  the  digestive 
tract  of  a  blood  sucking  invertebrate  are  usually  termed 
Haemoflagellates.     To  this  group  belong  the  trypanosomes 
and  leishmanias. 

2.  Description  of  species.     Among   the  more   important 
species  of  trypanosomes  that  are  pathogenic  in  lower  organ- 
isms are   T.   brucei  that  causes  nagana  in  mammals,    T. 
evansi  that  causes  surra  in  cattle,  camels,  etc.,  T.  equiperdum 
that  causes  dourine  in  horses,  T.  equinum  that  causes  "mal 
de  caderas"  in  horses  and  dogs,  and  T.  hippicum  that  causes 
murrina  in  mules.     The  number  of  species  of  trypanosomes 
that  are  pathogenic  in  man  is  not  certain;  those  usually 
recognized  are  T.  gdmbiense,  T.  rhodesiense,  and  T.  cruzi. 
Other  probable  species  are  T.  nigeriense  and  T.  castellanii. 


LEISHMANIASIS  19 

a.  T.  gambiense  (Plate  II,  Fig.  D,  1,  2,  3).  This  species 
was  named  by  Button  in  1902  from  specimens  taken  from  a 
fever  patient  in  Tropical  Africa.  It  is  the  cause  of  one  type 
of  sleeping  sickness.  It  ranges  from  18  to  30  microns  in 
length  and  1.5  to  2.5  microns  in  width.  Polymorphism  is 
exhibited  by  this  species  there  being  short,  stumpy  forms 
14  to  20  microns  long,  intermediate  forms  20  to  24  microns 
long,  and  long  forms  23  to  33  microns  long.  Tsetse  flies  of 
the  genus  Glossina  transmit  it  from  man  to  man. 

6.  T.  rhodesiense.  This  species  is  so  similar  to  T.  gam- 
biense in  morphology  that  the  two  are  difficult  to  separate. 
T.  rhodesiense  occurs  in  northwestern  Rhodesia,  and  Portu- 
guese and  German  East  Africa. 

c.  T.  cruzi  (Plate  II,  Fig.  E)  causes  Chagas'  disease  in 
Brazil.  It  is  about  20  microns  long  and  passes  through  a 
leishmania  stage,  especially  in  the  muscles.  The  bug, 
Triatoma,  is  the  transmitting  agent. 

3.  Methods  of  diagnosis.  Blood  films  should  be  made  and 
stained  as  described  for  the  malarial  parasites  (page  15). 
The  trypanosome  nature  of  the  organism  can  be  recognized 
at  once  but  the  species  diagnosis  is  very  difficult. 

Special  Literature  on  Trypanosomiasis 

LAVERAN,  A.,  AND  MESNIL,  F. :  Trypanosomes  and  Trypanosomiasis. 
2d  ed.  1000  pp.  Paris,  1912. 

Reports  Sleeping  Sickness  Commission,  Royal  Society  of  London, 
'  1903. 

Sleeping  Sickness  Bulletin,  London,  1908-1912. 

THIMM,  C.  A.:  Bibliography  of  Trypanosomiasis.  Sleeping  Sick- 
ness Bureau,  London,  1909. 

C.  Organisms  that  Cause  Leishmaniasis  in  Man 

1.  Classification.  The  organisms  that  cause  leishmaniasis 
are  included  among  the  Haemoflagellates,  and  belong  to  the 
genus  Leishmania.  Forms  with  flagella  usually  appear  only 
in  cultures. 


20  LEISHMANIASIS 

2.  Description  of  species.     Kala-azar  is  caused  by  Leish- 
mania   donovani;    infantile    kala-azar    resembles    kala-azar 
somewhat  and  is  caused  by  a  related  organism,  L.  infantum; 
oriental  sore  is  due  to  the  presence  of  L.  tropica;  and  espundia 
or  American  leishmaniasis  is  caused  by  L.  americana. 

a.  L.  donovani  (Plate  II,  Fig.  F,  1)  occurs  in  many  parts 
of  India,  Southern  China  and  Northern  Africa.     It  is  found 
only  occasionally  in  the  blood,  but  usually  lives  within  the 
cells  of  the  spleen,   liver,   lymph  glands   and   endothelial 
cells  of  the  blood  and  lymph  vessels.     The  organisms  are 
spherical  or  oval  in  shape  and  vary  from  2  to  4  microns  in 
diameter.     Each  contains  a  large  nucleus  and  a  small  rod- 
shaped  body.     Multiplication  occurs  in  the  invaded  cells, 
and  the  parasites,  when  they  break  out,  are  often  devoured 
by  leucocytes.    When  cultivated  outside  of  the  body  flagel- 
lated stages  appear.     The  bed  bug  has  been  suspected  as  the 
transmitting  agent. 

b.  L .  infantum  may  be  only  a  variety  of  L.  donovani; 
it  exists  in  certain  lands  bordering  on  the  Mediterranean, 
and  frequently  attacks  children.   "The  organism  resembles 
L.  donovani.     The  transmitting  agent  is  unknown  but  may 
be  the  dog  flea. 

c.  L.  tropica  (Plate  II,  Fig.  F,  2)  is  the  causative  agent  of 
oriental  sore  in  India,  Persia,  Syria,  Arabia  and  Northern 
Africa.     The  organisms  are  present  outside  and  within  the 
cells  of  the  sore.     They  are  often  spindle  shaped  and  about 
3  microns  long.     Flagellate  forms  have  been  recovered  from 
bed-bugs  48  hours  after  feeding  on  a  sore. 

d.  L.   americana   causes   espundia  in   certain   regions   of 
tropical  South  America.     Skin  sores  are  produced  by  the 
attacking  organisms. 

3.  Methods  of  diagnosis.     L.  donovani  and  L.  infantum 
should  be  looked  for  in  leucocytes  in  the  circulating  blood 
or  in   material   obtained   from   spleen   or   liver   puncture. 


FECAL   DIAGNOSIS   OF   INTESTINAL   PROTOZOA  21 

L.  tropica  and  L.  americana  can  be  obtained  directly  from 
the  sores.  Films  should  be  stained  as  described  for  the 
malarial  parasites. 

Special  Literature  on  Leishmaniasis 
LAVERAN,  A.:  Leishmanioses.    521  pp.    Paris,  1917. 

3.  INTESTINAL  PROTOZOA  OF  MAN 

A.  Methods -of  Fecal  Diagnosis  of  Intestinal  Protozoa 

The  method  of  fecal  diagnosis  employed  depends  some- 
what on  the  accuracy  of  the  results  desired  and  the  ability 
to  obtain  and  use  special  apparatus.  The  Donaldson  iodin- 
eosin  method  seems  to  be  the  quickest  and  easiest.  Con- 
centration methods  give  a  slightly  higher  percentage  of 
positives  and  the  Schaudinn  iron-haemotoxylin  smear 
method  is  very  useful  in  checking  up  doubtful  cases. 

L  Donaldson's  iodin-eosin  smear  method.  -  a.  Make  up  a 
fresh  solution  as  follows:  Saturated  solution  of  eosin  in 
normal  salt  solution,  two  parts;  5  per  cent  potassium  iodid 
in  normal  salt  solution  saturated  with  iodin,  one  part;  nor- 
mal salt  solution,  two  parts.  This  is  a  modification  of 
Donaldson's  stain,  due  to  Kofoid,  Kornhauser  and  Swezy. 

6.  "The  smear  is  prepared  for  microscopic  examination  by 
rubbing  out  a  minute  bit  of  the  feces  by  rolling  it  on  a  round 
applicator  stick  in  a  small  drop  of  normal  salt  solution  and 
then  in  an  adjacent  drop  of  iodin-eosin  stain.  A  single  cover 
is  placed  on  both  drops  and  the  smear  is  ready  for  immediate 
examination.  Living  flagellates  and  unstained  cysts  appear 
in  the  unstained  part.  In  the  stained  area  the  bacteria, 
fecal  particles  and  the  intestinal  yeasts  (except  the  larger 
forms)  stain  at  once.  Against  the  pink  background  the 
protozoan  cysts  stand  out  clearly  as  bright  spherules  which 
soon  become  tinged  with  the  iodin  to  varying  tones  of  yellow, 


22  FECAL   DIAGNOSIS   OP  INTESTINAL   PROTOZOA 

while  their  glycogen  filled  vacuoles,  when  present,  turn 
light  or  dark  brown  according  to  their  mass.  The  nuclei 
become  more  clearly  defined  as  the  iodin  penetrates,  espe- 
cially in  E.  [Entamoeba]  coli  and  E.  dysenteriae  [histolytica]. 
They  are  detected  with  difficulty  in  this  stain  in  E.  [Endo- 
limax]  nana."  (Kofoid,  Kornhauser,  and  Swezy.) 

2.  Cropper  and  Row's  concentration  method.     This  method 
as  modified  by  Boeck  is  as  follows:  "Take  at  least  one  gram 
of  the  stool  to  be  examined,  place  it  with  thirty  cubic  centi- 
meters of  normal  saline  solution  in  the  mixing  glass  and  stir 
for  at  least  ten  minutes  with  an  electric  mixer  such  as  is 
used  at  soda  fountains  in  mixing  drinks.     At  the  end  of  ten 
minutes,  while  still  stirring,  add  five  cubic  centimeters  of 
ether   and   stir   two   or   three  minutes   longer.     Pour  the 
emulsion  into  a  separatory  funnel  and  allow  to  stand  for  at 
least  five  to  seven  minutes,  during  which  the  cysts  will 
settle  to  the  bottom  in  the  saline  solution  and  debris  will 
float  in  the  ether  above.     The  funnel  used  for  this  separation 
has  a  funnel-shaped  bowl  with  steep  sides  contracting  to  a 
narrow  neck  above  the  turncock. 

At  the  end  of  this  period  of  standing,  the  saline  solution, 
about  fifteen  cubic  centimeters,  is  drawn  off  at  the  bottom 
of  the  separatory  funnel  into  a  centrifuge  tube  of  a  capacity 
of  fifteen  cubic  centimeters,  and  is  centrifuged  for  three 
minutes  at  1600  revolutions  per  minute.  The  supernatant 
fluid  is  then  drawn  off  and  the  residue  is  examined  micro- 
scopically for  the  cysts.  At  this  time  a  drop  of  neutral  red 
is  applied  to  a  small  amount  of  this  residue  to  procure  a 
sharper  contrast  between  the  cysts  and  the  surrounding 
debris.  By  this  method  a  faecal  examination  can  be  com- 
pleted in  twenty-five  to  thirty  minutes." 

3.  Schaudinn's      alcoholic     sublimate     iron-haematoxylin 
method,    a.  Prepare  a  fixing  solution  as  follows:  Saturated 
solution  of  mercuric  chloride  in  distilled  water,  200  cc.; 


INTESTINAL   ENTAMOEBAE    OF   MAN  23 

95  per  cent  alcohol,  100  cc.;  glacial  acetic  acid,  15  cc.     Heat 
to  65°C. 

b.  Make  a  smear  on  a  slide  and  while  still  wet  drop  it 
into  the  warm  fixing  solution.     Leave  there  for  about  ten 
minutes. 

c.  Immerse  in  70  per  cent  alcohol,  containing  a  trace  of 
iodine  30  minutes  to  24  hours;  wash  in  water  a  few  minutes; 
immerse  in  3.5  to  4  per  cent  aqueous  solution  of  iron  alum, 
one  to  4  hours;  wash  well  in  water;  transfer  to  0.5  per  cent 
aqueous  solution  of  haematoxylin ;  4  to  24  hours. 

d.  Differentiate  in  1.75  to  2  per  cent  iron  alum  solution 
until  enough  of  the  stain  has  been  removed.     This  is  best 
done  by  examining  under  the  microscope  at  frequent  inter- 
vals; wash  well  in  a  large  amount  of  water;  pass  up  through 
alcohols  to  absolute;  transfer  to  xylol;  mount  in  balsam. 

e.  Eosin  may  be  used  in  the  absolute  alcohol  if  a  counter 
stain  is  desired. 

Special  Literature  on  Methods  of  Diagnosis  of  Intestinal  Protozoa 

BOECK,  W.  C.:  A  Rapid  Method  for  the  Detection  of   Protozoan 

Cysts    in    Mammalian    Faeces.     University    of   California 

Publ.  in  Zool.,  Vol.  18,  pp.  145-149,  1917. 
CROPPER,  J.  W.,  AND  Row,  R.  W.  H. :  A  Method  of  Concentrating 

Entamoeba  Cysts  in  Stools.     Lancet,  Vol.  192,  pp.  179-182, 

1917. 
KOFOID,  C.  A.,  KORNHAUSER,  S.  I.,  AND  SWEZY,  O. :  Criterions  for 

Distinguishing  the  Endamoeba  of  Amebiasis    from  other 

Organisms.     Archives  of  Internal  Medicine,   Vol.  24,  pp. 

35-50,  1919. 

B.  Intestinal  Entamoebae  of  Man 

1.  Classification.  The  Entamoebae  belong  to  the  class 
Sarcodina.  The  members  of  this  class  are  characterized 
by  the  presence  of  locomotor  organs  in  the  form  of  tempo- 
rary finger  like  projections  of  protoplasm  called  pseudopodia 


24  INTESTINAL   ENTAMOEBAE    OF   MAN 

Many  free-living  species  are  common  in  fresh  water;  com- 
paratively few  species  are  parasitic.  Of  these  E.  histolytica 
(dysenteriae)  is  pathogenic  and  a  very  important  cause  of 
dysentery,  especially  in  tropical  and  subtropical  countries. 

2.  Species.     The   three   important   species   of   intestinal 
amoebae  that  have  been  found  within  the  intestine  of  man 
are  Entamoeba  histolytica,   E.   coli,   and  Endolimax  nana. 
To  diagnose  intestinal  disturbances  and  to, detect  carriers 
it  is  necessary  to  be  able  to  distinguish  both  the  motile 
stages  and  the  cysts  of  the  three  species.     Another  species 
of  Entamoeba  that  is  of  interest  is  E.  gingivalis  occuring  in 
the  mouth,  and  accused  of  causing  pyorrhea  alveolaris. 

3.  Distinguishing  features.     It  is  difficult  to  distinguish 
with  certainty  the  species  of  intestinal  amoebae  from  an 
examination  of  the  living  motile  stages.     The   appended 
table  presents  some  data  that  may  be  helpful.     The  most 
important   diagnostic   characteristics   are   the   presence   of 
ingested  blood  corpuscles  in  E.  histolytica  and  their  absence 
from  the  other  species,  and  the  distribution  of  the  chromatin 
within  the  nuclei  as  revealed  in  preparations  fixed  in  Schau- 
dinn's  fluid  and  stained  with  iron-haemotoxylin. 

4.  Distinguishing  features  of  cysts  of  intestinal    amoebae 
of  man.     The  cysts  of  the  Amoebae  of  man  are  more  impor- 
tant from  a  diagnostic  standpoint  than  the  motile  stages 
since  they  are  more  easily  identified  and  occur  more  fre- 
quently in  stools.    Nevertheless  the  variation  in  size  and 
in  nuclear  number  is  so  great  that  care  must  be  taken  in 
making  a  hurried  diagnosis  and  in  certain  cases  permanent 
preparations  stained  with  iron  haemotoxylin  are  advisable. 
The  accompanying  table  contrasts  the   characteristics  of 
the  cysts  of  the  three  principal  species.     As  a  rule  no  one 
feature  is  sufficient  for  a  certain  diagnosis  and  a  combination 
of  several  is  desirable. 


INTESTINAL   ENTAMOEBAE    OF   MAN 


25 


*-*    m    o 

n 


•- 

ii 


0 


- 


ll 


0 


•! 

' 


j 

P  CO  KH  M 


02 


26 


INTESTINAL  ENTAMOEBAE   OF  MAN 


(N 


8 


*  -*       *s    02 

rt      fn      rt) 

o    2   2 

SO     c3 
•*-"      in 

b   w 

|3 

£>8-S 

03     03     £3 
>     %     O 

~  a 
o  a 

1  oT  fe   o 
c3  -t-=>    o 

O 


03      CO      C      C  JH 

-J3    |    S    S         "g 

s  s  a  a     s  s? 


^03     03   .S    ." 
llj     " 

C    pj  'd 


•as 


5     3    ^      03 

is:g 

S     WO    O   ^ 


03   i— i    ,2 


ck 


1-  'gS  1.44 


^.SMH      3 

-v     O     0 


^H        & 


O 
&T3 


CQ  n 

fl    ^     -2 

^  -3  o 


1  2  -9  S 

r-r 

«ab  02  O 


«*-i     ^      03 
•^    03     03 

I  ss  .a 
o-a^ 

Hi 


0)     »i 

N 

rO      •£ 


1 


INTESTINAL  ENTAMOEBAE   OF  MAN 


27 


ill 


3  TO  *  *»    00 

.      £   -3  ra    rt  «    « 

f  II  1  1  I  1 

•^   ^  c       ^  r\ 


^    1 


O     o3 

it 

K 


>      OJ 

53 


2    fl 


ll-i^l 

P         o 


,st  highly  refractiv 
omogeneous,  porce 


o    P    o 


n-«i  i 

S  ^     o3  o3 


P 


Highly  rei 


ly  vi 
ible 


R 
In 


.-e  rs 


bfi 
O 
u 
>> 

O 


28  INTESTINAL   ENTAMOEBAE    OF   MAN 

a.  Cysts  of  Entamoeba  histolytica  (Plate  III,  Fig.  2). 
These  vary  in  diameter  from  5  to  20  microns  but  the  usual 
range  is  from  6  to  15  microns.  It  has  been  found  that  differ- 
ent races  exist  as  regards  size  and  that  in  one  patient  the 
cysts  may  be  only  7  to  8  microns  in  diameter,  in  another 
patient  they  may  be  from  10  to  11  microns,  and  in  others 
from  12  to  14  microns  in  diameter.  The  larger  races  may 
be  confused  with  small  cysts  of  E.  coli  and  the  smaller  races 
with  cysts  of  E.  nana. 

"The  cyst  wall  is  thin  and  rather  easily  penetrated  by  the 
iodin-eosin  stain  and  by  hematoxylin  stains.  In  the  iodin- 
eosin  stain  the  cytoplasm  is  first  a  bluish  gray  which  changes 
to  a  yellow  and  then  to  a  pink  color,  which  gradually  deepens 
to  red.  The  cytoplasm  is  unevenly  vacuolated  and  is  very 
finely  granular  but  the  granules  are  not  so  evenly  distributed 
as  in  E.  coli.  The  glycogen  mass,  when  present,  stains  a 
light  brown  in  iodin-eosin,  the  edges  gradually  shading 
into  the  surrounding  cytoplasm.  Sometimes  its  glycogen 
is  diffused  throughout  the  entire  cyst  which  then  stains  a 
yellowish  brown  color.  Chromatoid  rods  are  found  in  a 
majority  of  the  cysts,  represented  by  either  one  large  rod 
with  blunt  ends  nearly  the  diameter  of  the  cyst  in  length, 
or  by  several  smaller  rods  scattered  irregularly  in  the 
cytoplasm."  (Kofoid,  Kornhauser,  and  Swezy.) 

The  nuclei  furnish  the  best  basis  for  identification.  They 
range  in  number  from  1  to  4  according  to  percentages  listed 
in  the  accompanying  table.  When  stained  with  iodin-eosin 
they  become  visible  as  distinct  circles  with  a  central  chro- 
matin  granule,  and  many  small  granules  distributed  rather 
evenly  on  the  nuclear  membrane.  In  doubtful  cases  perma- 
nent iron  haemotoxylin  preparations  should  be  made. 

6.  Cysts  of  Entamoeba  coli  (Plate  III,  Fig.  4).  Cysts 
of  E.  coli  range  from  11  to  35  microns  in  diameter  but  usually 
lie  within  the  limits  of  17  to  22  microns.  They  are  usually 


PLATE  III 


8 


10 


INTESTINAL  AMOEBAE,  BLASTOCYSTIS,  YEAST  AND  MOLD 

Entamoeba  histolytica.  (1)  Motile  vegetative  stage.  (2)  Quad- 
rinucleate  cyst  with  chromatoidal  rod. 

Entamoeba  coli.  (3)  Motile,  vegetative  stage.  (4)  Cyst  with 
eight  nuclei. 

Endolimax  nana.  (5)  Living  motile,  vegetative  stage.  (6) 
Cyst  with  four  nuclei.  (7)  Ellipsoidal  cyst  with  four  nuclei.  (8) 
Blastocystis  hominis,  small  stage.  (9)  Budding  yeast.  (10)  Intes- 
tinal mold.  Figs.  6,  8,  9,  10  are  magnified  2800  diameters  (from 
Kofoid,  Kornhauser,  and  Swezy  in  Archives  of  Internal  Medicine. 
Figures  1,  2,  3,  4,  7  (from  Dobell)  are  magnified,  1  X  1000,  2  X  2500, 
3  X  1800,  4  X  2500,  7  X  2500. 

29 


30  INTESTINAL   ENTAMOEBAE   OF  MAN 

spheroidal  and  possess  a  thicker  wall  than  those  of  E. 
histolytica.  When  stained  with  iodin-eosin  the  cytoplasm 
has  a  uniformly  granular  appearance;  glycogen  is  seldom 
present;  and  the  nuclei,  usually  eight  in  number,  are  clearly 
visible  and  possess  a  central  granule  often  eccentric  and 
a  layer  of  large  granules  of  chromatin  on  the  nuclear 
membrane. 

c.  Cysts  of  Endolimax  nana  (Plate  III,  Figs.  6,  7).  Cysts 
of  E.  nana  range  in  diameter  from  3  to  16  microns  but  are 
usually  no  less  than  5  and  no  greater  than  12  microns  in 
diameter.  Small  and  large  races  occur  in  this  species  as 
in  E.  histolytica',  the  former  vary  from  4  to  8  microns  and 
are  generally  ellipsoidal,  the  larger  races  from  10  to  15 
microns  and  are  often  ovoidal  in  shape.  The  nuclei  furnish 
the  best  diagnostic  character.  They  are  often  obscured 
by  the  many  small  vacuoles  in  the  cytoplasm  and  in  doubtful 
cases  cysts  must  be  stained  in  iron  haemotoxylin  to  bring 
out  their  characteristics.  No  central  chromatin  granule  is 
present  but  all  of  the  chromatin  is  usually  aggregated  in 
one  large  mass  and  one  or  more  smaller  masses. 

Special  Literature  on  Entamoebae 

CRAIG,  C.  F.:  The  Parasitic  Amoebae  of  Man.  Philadelphia,  1911. 
DOBELL,  C.,  AND  JEPPS,  M.  W. :  A  Study  of  the  Diverse  Races  of 

Entamoeba  histolytica.    Parasitology,  Vol.  10,  pp.  320-351, 

1918. 

DOBELL,  C.:  The  Amoebae  Living  in  Man.  155  pp.  London,  1919. 
KOFOID,  C.  A.,  KORNHATJSER,  S.  I.,  AND  SWEZY,  O. :  Criterions  for 

Distinguishing  the  Endamoeba  of  Amebiasis  from   Other 

Organisms.    Archives  of  Internal  Medicine,   Vol.  24,   pp. 

35-50,  1919. 
WENYON,  C.  M.,  AND  O'CONNOR,  F.  W.:  Human  Intestinal  Protozoa 

in  the  Near  East.    218  pp.    London,  1917. 


INTESTINAL   FLAGELLATES    OF   MAN  31 

C.  Intestinal  Flagellates  of  Man 

1.  Classification.     The  intestinal  flagellates  belong  to  the 
class  Mastigophora  and  are  characterized  by  the  presence 
of  one  or  more  flagella.     They  are  representatives  of  two 
orders,  (1)  the  Polymastigina  and  (2)  the  Protomonadina. 
The  Polymastigina  possess  from  3  to  8  flagella  whereas  the 
Protomonadina  have  only  one  or  two.     Most  of  the  impor- 
tant species  belong  to  the  former.     There  is  great  need  of 
careful  investigation  of  the  intestinal  flagellates  since  only 
a  few  are  known  at  all  well,  and  many  species  have  been 
described  and  named  but  are  not  yet  well  established.     The 
best  known  forms  are  Giardia  (Lamblia)  intestinalis,  Tri- 
chomonas   hominis,   and   Chilomastix    (Tetramitus)    mesnili. 
These  occur  so  frequently  that  they  require  more  extended 
treatment  than  those  less  well  known.     Among  the  latter 
are  Enteromonas  hominis,  Enibadomonas  (Waskia)  intestin- 
alis,   Tricercomonas   hominis,    Tetratrichomonas  intestinalis, 
Pentatrichomonas    intestinalis,    Oicomonas    hominis,   Cerco- 
monas  longicauda,  and  Prowazekia  asiatica. 

2.  Description  of  Species,     a.  Giardia  (Lamblia)  intestin- 
alis (Plate  IV,  Fig.  6).     Motile  stage:  When  in  the  motile 
stage  this  species  is  pear-shaped,  from  10  to  21  microns  long 
and  from  5  to  12  microns  wide.     The  anterior  half  of  the 
organism  bears  a  depression  which  acts  as  a  sucking  disk 
for  attachment  to  intestinal  epithelial  cells.    Two  nuclei, 
one  or  two  axostyles,  and  four  pairs  of  flagella  are  present 
as  shown  in  the  figure.     Specimens  in  the  motile  stage  are 
not  so  frequently  observed  in  feces  as  are  the  cysts.     Rats, 
mice  and  rabbits  are  often  infected  with  what  are  probably 
distinct  species  of  Giardias  and  those  who  wish  to  gain  a 
preliminary  knowledge  of  these  organisms  should  examine 
material  from  the  duodenum  of  these  animals. 


PLATE  IV 


PLATE  IV 
INTESTINAL  FLAGELLATES,  CILIATES  AND  COCCIDIA  OF  MAN 

1.  Balantidium  coli.  (X  585,  after  Leuckart.)  2.  Chilomastix 
mesnili.  (X  2335,  after  Wenyon.)  3.  Chilomastix  mesnili,  cyst. 
(X  2335  after  Kofoid,  Kornhauser  and  Swezy.)  4.  Trichomonas 
hominis.  (X  2335,  after  Wenyon.)  5.  Isospora  hominis.  (X  1775, 
after  Dobell.)  6.  Giardia  (Lamblia)  intestinalis.  (X  2335,  drawn 
by  Dr.  C.  E.  Simon.)  7.  Giardia  intestinalis,  cyst.  (X  2335,  after 
Kofoid,  Kornhauser  and  Swezy.) 

32 


INTESTINAL    FLAGELLATES    OF   MAN  33 

Cysts  (Plate  IV,  Fig.  7):  These  are  oval  bodies  10  to 
15  microns  long  and  7  to  9  microns  wide.  Two  or  four  nuclei 
are  present,  usually  at  one  end,  and  two  longitudinal  curved 
axostyles  extend  down  the  center  of  the  cyst.  Two  rod- 
shaped  parabasal  bodies  and  a  variable  number  of  loops 
which  probably  represent  the  cytostomal  fibrils  are  also 
embedded  in  the  cytoplasm. 

b.  Trichomonas  hominis  (Plate  IV,  Fig.  4).     Motile  stage: 
This  is  a  pear-shaped  organism  measuring  from  10  to  15 
microns  long  and  3  to  4  microns  wide.     An  axostyle  is 
situated  near  the  center  of  the  body  and  projects  beyond 
the  posterior  end.     Along  one  side  is  an  undulating  mem- 
brane terminating  at  the  posterior  end  in  a  flagellum.     Three 
other  flagella  extend  out  from  the  anterior  end.     The  cyto- 
plasm is  vacuolated.     Within  it,  near  the  anterior  end  are 
a  nucleus  containing  scattered  chromatin  granules  and  a 
parabasal   rod.     Reproduction    is    by    binary   fission.     No 
cysts  have  yet  been  identified  with  certainty.     Specimens 
of  T.  augusta,  which  resemble  the  species  found  in  man,  are 
abundant  in  the  intestine  of  the  frog. 

c.  Chilomastix   (Tetramitus)   mesnili   (Plate   IV,   Fig.   2). 
Motile  stage:  This  may  also  be  described  as  a  pear-shaped 
organism,  rounded  anteriorly  and  pointed  posteriorly.     It 
varies  considerably  in  size  ranging  from  7  to  8  microns  in 
length.     Three  flagella  extend  out  freely  from  the  anterior 
end,  and  a  fourth  flagellum  lies  within  the  cytostome.     The 
cytostome  is  about  one-half  the  length  of  the  body.     A  large 
spherical  or  oval  nucleus  lies  near  the  anterior  end. 

Cysts  (Plate  IV,  Fig.  3) :  These  are  usually  pyriform  but 
often  spherical  and  measure  6  to  9  microns  in  diameter.  A 
single  nucleus  is  present  containing  a  chromatin  granule 
near  the  center  and  chromatin  masses  on  the  membrane. 
Extending  across  the  cyst  are  the  remains  of  the  cytostome 
characteristic  of  this  species. 


34  INTESTINAL   COCCIDIA   OF   MAN 

3.  Methods  of  diagnosis.  The  motile  forms  of  intestinal 
flagellates  may  be  seen  moving  about  in  the  feces  if  material 
is  examined  shortly  after  being  passed  by  the  patient.  Both 
motile  forms  and  cysts  may  appear  when  treated  according 
to  the  methods  described  on  page  22. 

Special  Literature  on  Intestinal  Flagellates 

CHALMERS,  A.  D.,  AND  PEKKOLA,  W. :  Chilomastix  mesnili.  Annals 
Trop.  Med.  and  Parasit.  Vol.  11,  pp.  213-264,  1918. 

KOFOID,  C.  A.,  KORNHAUSER,  S.  I.,  AND  SWEZY,  O.  I  Criterions  for 
Distinguishing  the  Endamoeba  of  Amoebiasis  from  other 
Organisms.  Archives  of  Internal  Medicine,  Vol.  24,  pp. 
35-50,  1919. 

WENYON,  C.  M.,  AND  O'CONNOR,  F.  W.:  Human  Intestinal  Protozoa 
in  the  Near  East.  218  pp.  London,  1917. 

D.  Intestinal  Coccidia  of  Man 

1.  Classification.     The  Coccidia  are  Sporozoa  of  the  sub- 
class Telosporidia.     They  are  as  a  rule  parasitic  in  epithelial 
cells  of  vertebrates  and  invertebrates,   and  reproduce  by 
both  schizogony  and  sporogony.     Among  the  best  known 
Coccidia  are  Coccidium  schubergi  of  the  centipede,  Eimeria 
stiedae  of  the  rabbit,  and  E.  avium  in  birds.     Many  other 
species  are  known,  but  not  in  detail. 

2.  Description  of  species.    Prior  to  the  year  1915   only 
ten  cases  of  coccidiosis  in  man  had  been  reported  and  these 
were  supposed  to  be  due  to  the  same  parasites  as  those  found 
in  rabbits,  cats  and  dogs.     Recently  many  more  cases  have 
been  discovered  and  it  seems  probable  that  the  human 
coccidia  are  more  numerous  than  heretofore  suspected. 

a.  Isospora  hominis  (Plate  IV,  Fig.  5).  This  species  was 
first  described  by  Virchow  in  1860.  Wenyon  and  others 
have  recently  reported  over  sixty  cases  of  infection  of  soldiers 
suffering  from  dysentery  and  enteritis  and  invalided  to 
England  from  Gallipoli.  This  species  has  also  been  recorded 


INTESTINAL    COCCIDIA   OF   MAN  35 

from  men  who  had  been  in  Egypt,  Saloniki,  and  Meso- 
potamia. 

The  oocysts  in  the  feces  are  elongate,  ovoid  in  form,  25 
to  33  microns  in  length,  and  12.5  to  16  microns  in  width. 
Two  sporoblasts  are  formed  in  each  oocyst  and  each  sporo- 
blast  produces  four  vermiform  sporozoites. 

b.  Eimeria  wvnyoni  was  discovered  by  Wenyon  in  1915 
and  four  cases  have  been  recorded.     The  oocyst  is  spherical, 
about  20  microns  in  diameter  and  with  an  outer  rough 
surface.    .Within  the  oocyst  are  four  sporoblasts  each  con- 
taining two  sporozoites.     These  are  already  differentiated 
when  the  oocysts  are  passed  by  the  patient. 

c.  Eimeria  oxyspora  is  known  from  only  one  case.     The 
oocyst   is   spherical   and   about   36   microns   in   diameter. 
Within  it  are  four  sporoblasts  each  with  two  sporozoites. 

3.  Methods  of  Diagnosis.  The  oocysts  of  coccidia  appear 
when  the  feces  are  treated  as  described  on  page  88.  Perhaps 
the  best  way  to  become  acquainted  with  them  is  to  examine 
the  feces  of  rabbits,  which  are  very  highly  infected.  Freshly 
passed  oocysts  of  the  rabbit  coccidium,  Eimeria  stiedae, 
are  almost  filled  with  protoplasm.  If  the  feces  are  mixed 
with  water  the  oocysts  will  develop  and  within  about  48 
hours  four  sporoblasts  will  form  within  them,  each  of  which 
will  be  seen  to  contain  two  sporozoites. 

Special  Literature  on  Coccidia 

DOBELL,  C.:  A  Revision  of  the  Coccidia  Parasitic  in  Man.  Para- 
sitology,  Vol.  11,  pp.  147-197,  1919. 

WENYON,  C.  M.:  Observations  on  the  Common  Intestinal  Protozoa 
of  Man,  Their  Diagnosis  and  Pathogenicity.  Journal 
Royal  Army  Medical  Corps,  Vol.  25,  p.  600,  1915. 


36  INTESTINAL    CILIATES    OF   MAN 

E.  Intestinal  Ciliates  of  Man 

L  Classification.  The  ciliates  belong  to  the  class  Infusoria. 
The  members  of  this  class  are  characterized  by  the  presence 
of  locomotor  organs  in  the  form  of  cilia.  Most  of  them 
are  free  living.  Many  parasitic  species  occur  in  vertebrates 
and  invertebrates,  but  only  one  species,  Balantidium  coli, 
has  been  found  with  frequency  in  man.  Other  species  have 
been  recorded  from  man  but  not  often  enough  to  warrant 
their  inclusion  here. 

2.  Description  of  species,     a.  Balantidium  coli  (Plate  IV, 
Fig.  1) :  This  is  a  very  large  Protozoon,  measuring  from  60 
to  100  microns  in  length  and  from  50  to  70  microns  in  breadth. 
It  is  oval  in  shape  and  covered  with  cilia  arranged  in  parallel 
rows,  giving  it  a  striated  appearance.     The  macronucleus 
is  large  and  bean  shaped  and  near  it  lies  a  small  spherical 
micronucleus.     At   the   anterior   end   is   a   funnel   shaped 
peristome,  and  at  the  posterior  end  a  terminal  cytopyge 
(anus).     Two    contractile    vacuoles    are    present.     Repro- 
duction is  by  binary  fission.     Conjugation  and  encystment 
occur. 

6.  Nyctotherus:  Three  species  of  this  genus  have  been 
reported  from  man  but  are  so  rare  that  they  need  not  be 
.described  here. 

3.  Method  of  diagnosis.     There  is  nothing  in  fecal  material 
that  is  likely  to  be  confused  with  these  ciliates  on  account 
of  their  large  size  and  distinctive  characteristics.     A  species 
that  may  be  Balantidium  coli  is  abundant  in  the  intestine 
of  the  pig  and  another  species  occurs  in  the  rectum  of  the 
frog.     A  species  of  Nyctotherus  lives  in  the  rectum  of  the 
frog  and  another  species  in  the  rectum  of  the  cockroach. 
Anyone  wishing  to  study  these  parasites  can  easily  obtain 
them  from  these  animals. 


VEGETABLE    ORGANISMS    IN   HUMAN    FECES  37 

F.  Some  Vegetable  Organisms  in  Human  Feces 

There  are  many  bodies  that  occur  in  human  feces  that 
may  be  mistaken  for  the  motile  stages  or  cysts  of  Protozoa. 
Of  these  the  most  confusing  are  probably  the  vegetable 
organisms  known  as  Blastocystis  hominis,  and  the  yeasts. 

1.  Blastocystis  hominis  (Plate  III,  Fig.  8).     This  organism 
is  frequently  found  in  stools  containing  intestinal  Protozoa 
and  often  occurs  when  Protozoa  are  absent.     It  is  usually 
spheroidal  in  shape  and  very  variable  in  size,  ranging  from 
3  to  20  microns  in  diameter.     The  smaller  specimens  are 
often   oval,   with  granular  contents   that  stain  yellow  in 
iodin-eosin  stain,  and  with  a  peripheral  film  of  pink.     They 
may  easily  be  confused  with  Endolimax  nana.     The  large 
specimens  possess  a  refractive  homogeneous  center  and  an 
outer  granular  coat  which  contains  refractive  granules  and 
stains  pink  in  iodin-eosin  stain. 

2.  Intestinal  yeasts  (Plate  III,  Fig.  9).     Certain  yeasts 
are  normally  present  in  human  feces  and  may  be  mistaken 
for  protozoan  cysts.     In  the  iodin-eosin  stain  they  take  on 
a  red  color  at  once  which  is  sufficient  to  distinguish  them 
from  protozoan  cysts.     Some  of  them  also  are  found  in  the 
process  of  budding.     Other  cyst-like  bodies  also  occur  in 
human  feces;  these  may  be  degenerating  organisms,  or  the 
spores  of  molds  (Plate  III,  Fig.  10).     Certain  of  these  may 
correspond  to  what  Wenyon  and  others  have  called  "iodine 
cysts;"  bodies  that  have  been  identified  by  Dobell  as  belong- 
ing to  an  amoeba  to  which  the  name  lodamoeba  butschlii 
has  been  given. 


PART  II.  WORMS  PARASITIC  IN  MAN 
WILLIAM  W.  CORT 

1.  INTRODUCTION  TO  THE  PARASITIC  WORMS 

The  endoparasitic  helminths  belong  to  the  classes  Trema- 
toda  and  Cestoda  under  the  phylum  Platyhelminthes  and 
to  the  class  Nematoda  under  the  phylum  Nemathelminthes. 
The  trematodes,  commonly  known  as  flukes,  are  important 
parasites  of  man  especially  in  the  Far  East  and  Africa  where 
they  produce  such  dangerous  diseases  as  bilharziasis,  Japan- 
ese schistosomiasis,  clonorchiasis  and  paragonimiasis.  The 
cestodes  or  tapeworms  are  practically  cosmopolitan  in 
distribution.  While  they  are  frequently  encountered  their 
relation  to  disease  is  not  so  definite  except  in  the  case  of 
Echinococcus,  which  in  man  produces  hydatids  of  the  liver 
and  other  organs.  The  nematodes  or  round  worms  are  the 
most  prevalent  and  important  helminths  of  man.  In  this 
group  belong  the  organisms  which  produce  hookworm  dis- 
ease, filariasis  and  trichinosis.  It  is  only  since  medicine 
and  public  health  work  have  come  to  be  considered  as 
world  problems  that  the  diseases  produced  by  parasitic 
worms  have  come  into  prominence.  Since  such  diseases 
are  very  prevalent  in  the  Tropics  and  Orient  and  there  is 
constant  danger  of  their  spread  into  new  regions  with 
commerce  and  immigration,  it  is  important  that  the  medical 
man,  wherever  located,  should  be  acquainted  with  their 
manifestations  and  methods  of  diagnosis,  and  should  be 
able  to  identify  the  worms  which  produce  them  and  know 
their  methods  of  entrance  into  man. 

2.  DIAGNOSIS  OF  DISEASES  CAUSED  BY  PARASITIC  WORMS 

In  diseases  produced  by  parasitic  worms  the  clinical 
picture  is  usually  not  very  clear  cut  and  the  symptoms  are 
easily  confused  with  those  of  other  diseases.  In  infestations 

38 


DIAGNOSIS  OF  DISEASES  CAUSED  BY  PAEASITIC  WORMS       39 

with  Schistosoma  haematobium  and  Paragonimus  westermanii 
the  eggs  escape  with  the  urine  and  sputum  respectively,  so 
diagnosis  of  these  forms  must  be  made  by  microscopical 
examination  of  these  media.  In  the  Filaridae,  the  larvae 
are  carried  from  one  host  to  another  by  the  mosquito  and 
diagnosis  is  made  as  in  malaria  by  the  examination  of  blood 
smears.  In  the  majority  of  these  diseases  however,  the  eggs 
or  larvae  of  the  worms  escape  with  the  feces  and  an  accurate 
diagnosis  can  be  made  by  microscopical  examination  of  the 
stools. 

In  diagnosis  by  fecal  examination  the  technique  used  is 
of  very  great  importance.  The  number  of  worms  present 
varies  greatly  in  the  different  cases  and  even  with  the  best 
possible  technique  it  is  probable  that  not  all  cases  will  be 
detected.  Since  in  the  lighter  infestations  there  are  usually 
no  symptoms  present  such  individuals  are  usually  classed 
as  "carriers."  Since  with  almost  all  the  parasitic  worms 
of  man  an  injurious  effect  is  produced  in  light  infestations 
as  well  as  heavy,  although  there  may  be  no  noticeable 
symptoms,  and  since  every  "carrier"  is  a  potential  spreader 
of  the  disease  it  would  seem  that  the  greatest  possible 
accuracy  in  diagnosis  is  desirable.  There  are  however  other 
factors  to  be  considered.  Greater  accuracy  usually  means 
fewer  examinations.  When  as  in  hookworm  campaigns 
the  examinations  to  be  made  are  many  and  the  workers 
few,  a  compromise  must  be  made  between  thoroughness  and 
speed.  Under  hospital  conditions  where  there  are  only  a 
comparatively  few  examinations  to  be  made  it  would  seem 
to  be  advisable  to  use  the  slower  but  more  critical  methods. 
In  field  campaigns  or  surveys,  however,  where  thousands  of 
examinations  must  be  made,  often  by  microscopists  who 
have  no  special  scientific  training,  and  under  conditions 
where  it  is  difficult  to  obtain  or  use  complicated  apparatus, 
simple,  more  rapid  methods  of  examination  would  certainly 


40       DIAGNOSIS  OF  DISEASES  CAUSED  BY  PARASITIC  WORMS 

be  preferable.  Descriptions  will  be  given  of  the  smear 
method,  the  centrifugation  method,  and  the  brine  flotation- 
loop  method  of  fecal  examination. 

Smear  method:  The  smear  is  the  most  direct  and  simple 
method  of  fecal  examination.  In  preparing  a  smear  a  small 
bit  of  the  feces  to  be  examined  is  mixed  with  distilled  or 
filtered  water  on  an  ordinary  glass  microscopical  slide.  The 
smear  should  be  mixed  in  enough  water  so  that  ordinary 
print  can  be  seen  through  it.  If  the  smears  are  too  dense 
it  greatly  lessens  the  chances  of  finding  the  eggs.  The 
accuracy  of  the  smear  method  depends  on  the  number  of 
slides  examined.  The  examination  of  a  single  smear  will 
instantly  detect  heavy  infestations,  but  to  detect  lighter 
cases  would  require  the  examination  of  such  a  large  number 
of  slides  that  the  method  loses  its  value. 

Centrifugation  method:  The  object  of  centrifugation  is 
to  wash  and  concentrate  the  fecal  material  to  be  examined. 
Various  modifications  of  this  method  have  been  used.  All 
have  as  common  features  (1)  the  thorough  mixing  of  a 
piece  of  fecal  material,  with  distilled  or  filtered  water,  (2) 
the  straining  of  this  mixture  through  a  sieve  or  piece  of 
cheese  cloth  to  remove  larger  particles,  (3)  the  centrifugation 
of  the  suspension  to  concentrate  the  material,  and  (4)  the 
making  of  smears  of  the  residue  for  examination.  Usually 
the  sample  should  be  washed  and  centrifugated  about  three 
times.  The  time  of  centrifugation  should  be  very  short 
because  the  eggs  are  easily  thrown  down.  The  simplest 
application  of  the  centrifugation  method  is  that  used  at  the 
Immigration  Hospital  at  Angel  Island,  California,  for 
examinations  of  oriental  immigrants.  Here  the  sample 
used  is  about  the  size  of  the  thumb,  and  the  sediment  after 
centrifugation  is  spread  over  the  whole  surface  of  a  1  by  3 
slide  and  is  examined  without  a  cover  glass.  In  the  hook- 
worm campaigns  of  the  Rockefeller  International  Health 


DIAGNOSIS  OF  DISEASES  CAUSED  BY  PARASITIC  WORMS       41 

Board  in  the  West  Indies  a  combination  of  the  smear  and 
centrifugation  methods  is  used.  Two  or  three  smears  are 
made  from  each  sample  to  eliminate  the  heaviest  cases  and 
the  negatives  are  examined  after  centrifugation. 

The  brine  flotation-loop  method:  This  technique  was 
devised  by  Kofoid  and  Barber  for  the  examination  for  hook- 
worm disease  of  men  in  the  Army  from  the  Southern  States 
during  the  war.  In  this  method  a  fecal  sample  is  thoroughly 
mixed  with  concentrated  brine.  The  coarse  float  is  forced 
below  the  surface  with  a  disc  of  .No.  0  steel  wool  and  the 
container  allowed  to  stand  for  about  an  hour  for  the  eggs 
to  ascend.  The  surface  film  is  then  looped  off  onto  a  slide 
and  examined  without  a  cover  glass.  The  microscope  must 
be  focused  on  the  surface  of  the  drop  on  the  slide.  This 
method  gives  fine  concentration  and  a  very  clear  preparation 
for  study.  It  is  without  doubt  the  best  and  quickest  method 
of  examination  for  hookworm  eggs  and  when  combined  with 
a  preliminary  single  smear  to  eliminate  the  heaviest  cases 
can  be  highly  recommended  for  use  in  hookworm  campaigns. 
Unfortunately  operculate  eggs  are  not  floated  by  this  method 
so  that  it  cannot  be  used  where  it  is  desirable  to  detect  such 
forms  as  the  liver  fluke,  Clonorchis  sinensis,  and  the  fish 
tape  worm,  Diphyllobothrium  latum.  Also  it  is  of  no  value 
in  the  detection  of  Strongyloides  stercoralis  since  the  larvae, 
which  in  this  case  are  found  in  the  stools,  are  also  not 
floated. 

Ordinary  routine  fecal  examinations  are  not  sufficient  to 
detect  the  presence  of  all  types  of  eggs.  Since  the  eggs  of 
Schistosoma  japonicum  and  especially  S.  mansoni  are  not 
evenly  distributed  throughout  the  stool  it  is  necessary  to 
take  special  precautions  in  taking  the  sample  when  examin- 
ing for  these  forms.  The  eggs  of  Enter obius  vermicularis  are 
rarely  found  in  routine  fecal  examinations,  but  this  species 
offers  little  difficulty  in  diagnosis  on  account  of  the  anal 


42  KEY   FOR  DIAGNOSIS   OF  HUMAN   HELMINTHS 

itching  and  the  finding  of  mature  females  and  eggs  in  the 
stools.  The  following  key  is  included  to  aid  in  the  diagnosis 
of  the  diseases  produced  by  parasitic  worms. 

3.  KEY  FOR  DIAGNOSIS  OF  HUMAN  HELMINTHS 

A.  Larvae,  microfilariae,  in  blood  (the  part  of  the  key  on  the  micro- 

filariae  is  adapted  from  Stitt). 
1.  Sheath  present. 

a.  No  periodicity. 

Filaria  philippinensis.  Tightly  fitting  sheath,  not 
flattened  out  beyond  extremities;  tail  pointed  and 
abruptly  attenuated;  290ju  to  320/i  by  5ju. 

b.  Periodicity. 

1.  Noctural  periodicity. 

Filaria  bancrofti  (Plate  VI,  Fig.  3).  Tail 
pointed;  sheath  loose;  V-spot  90/i  from  head; 
break  in  cells  5(V  from  head;  300/x  by  7.5/i. 

2.  Diurnal  periodicity. 

Loa  loa  (Filaria  loo)   (Plate  VI,  Fig.  2).    Tail 
pointed;  sheath  loose;  V-spot  GO/*  to  70/z  from 
head;  break  in  cells  40/x  from  head;  245/x  by  7/i. 
II.  Sheath  absent;  no  periodicity. 

a.  Tail  blunt 

Acanthocheilonema  perstana  (Filaria  perstans)  (Plate 
VI,  Fig.  4).  190/i  to  200^  by  4.5/x  to  5/x. 

b.  Tail  sharply  pointed. 

1.  200M  by  5/t. 

Filaria  ozzardi  (F.  demarquayi) .  (Plate  VI, 
Fig,  1). 

2.  250/i  to  300/*  by  5/x  to  7/*. 

Onchocerca  volvulus.  Microfilariae  of  this  species 
have  not  been  seen  in  blood  but  only  in  lymph 
spaces  around  females. 

B.  Larvae  in  feces,  rhabditiform  state. 

I.  Length  of  buccal  cavity  only  one-half  the  diameter  of 

body. 

Strorigyloides  stercoralis  (Plate  VI,  Fig.  8).    200/*  to  250/i 
by  13/i  to  15/z;  genital  anlage  about  30/*  in  length. 


KEY*  FOR   DIAGNOSIS   OP   HUMAN   HELMINTHS  43 

TT.  Length  of  buccal  cavity  almost  equal  to  diameter  of  body. 
Ancylostoma  duodenale*  or  Necator  americanus  (Plate  VI, 
Fig.  10).    Expansion  at  the  base  of  buccal  cavity; 
genital  anlage  only  4/i  to  5ju  in  length. 

C.  Eggs  in  urine. 

Schistosoma  haematobium  (Plate  V,  Fig.  3).  Large  ter- 
minal spine;  contain  fully  developed  miracidium;  120/z 
to  150/i  by  40/Lt  to  60/i. 

D.  Eggs  in  Sputum. 

Paragonimus  westermanii^  (Plate  V,  Fig.  5).  Operculate: 
brownish  or  yellowish  brown  in  color;  contains  fertilized 
ovum  surrounded  by  yolk  cells;  80/i  to  100/i  by  52/z  to  75/* 

E.  Eggs  in  Feces. 

I.  Operculum  present. 

a.  Eggs  under  40ju  in  length;  contain  a  fully  developed 
miracidium. 

1.  Operculum  sharply  defined  with  shell  projecting 

slightly  behind  its  edge. 

(a)  OpisthorcMs  felineus%.    Size  of  egg  30/t  by 

11/z. 

(b)  Clonorchis   sinensisl    (Plate   V,    Fig.   6). 

Average  size  of  egg,  29/x  by  16/t. 

(c)  Clonorchis    endemicus%.    Average    size    of 

eggs  2Qn  by  17/z. 

2.  Operculum  not  sharply  defined,  the.  shape  being 

regularly  oval, 
(a)  Egg  brownish  with  thick  shell. 

Heterophyes  heterophyes.    Average  size  of 
eggs  30/z  by  17/x. 

*  Diagnosis  in  the  case  of  the  hookworms  is  usually  made  from 
eggs  in  the  stools.  In  old  samples  sometimes  the  eggs  will  have  had 
time  to  hatch  and  then  the  larvae  must  be  carefully  distinguished 
from  those  of  Strongyloides  stercoralis. 

t  Eggs  of  this  form  are  also  found  in  feces  from  swallowing  of 
sputum  by  the  patient. 

t  It  is  difficult  if  not  impossible  in  the  present  state  of  our  knowl- 
edge to  distinguish  these  three  species  by  their  eggs.  Since  their 
geographical  distribution  differs,  the  locality  from  which  the  patient 
comes  will  usually  give  a  clue  to  the  specific  identity  of  the  worms. 


44  KEY  FOR    DIAGNOSIS    OF   HUMAN   HELMINTHS 


PLATE  V 
EGGS  OF  THE  MOST  IMPORTANT  HUMAN  HELMINTHS 

All  the  drawings  are  original  except  figures  7,  8,  9,  and  11,  which 
are  modified  from  other  authors.  All  the  figures  are  at  the  same  mag- 
nification. 

1.  Fasciolopsis  buskii.  2.  Schistosoma  mansoni.  3.  Schistosoma 
haematobium.  4.  Schistosoma  japonicum.  5.  Paragonimus  wester- 
manii.  6.  Clonorchis  sinensis.  7.  Metagonimus  yokogawai.  8. 
Taenia  saginata.  9.  Taenia  solium.  10.  Hymenolepis  nana.  11. 
Hymenolepis  diminuta.  12.  Diphyllobothrium  latum  (Dibothrio- 
cephalus  latus} .  13.  A scaris  lumbricoides  (egg  without  outer  coating) . 
14.  Ascaris  lumbricoides  (abnormal  egg).  15.  Ascaris  lumbricoides. 
16.  Trichuris  trichiura.  17  and  18.  Hookworm  eggs.  19.  Enterobius 
vermicularis  (Oxyuris  vermicular  is).  20.  Oxyuris  incognita.  21. 
Trichostrongylus  orientalis. 


PLATE  V 


17 


46  KEY   FOR   DIAGNOSIS   OF   HUMAN   HELMINTHS 


PLATE  VI 

Fig.  1.'  Larval  stage  of  Filaria  ozzardi  (F.  demarquayi).  After 
Fulleborn. 

Fig.  2.  Larval  stage  of  Loa  loa  (Microfilaria  diurna).  After 
Fulleborn. 

Fig.  3.  Larval  stage  of  Filaria  bancrofti  (Microfilaria  nocturna). 
After  Fulleborn. 

Fig.  4.  Larval  stage  of  Acanthocheilonema  perstans  (Microfilaria 
Persians').  After  Fulleborn. 

Fig.  5.  Adult  parasitic  female  of  Strongyloides  stercoralis.  After 
Looss. 

Fig.  6  and  Fig.  7.  Adults,  male  and  female,  of  the  free  living  gen- 
eration of  Strongyloides  stercoralis.  Afcber  Looss. 

Fig.  8.  Rhabditif  orm  larva  of  Strongyloides  stercoralis  j  ust  hatched 
from  the  egg.  After  Looss. 

Fig.  9.  Filariform  infective  larva  of  Strongyloides  stercoralis. 
After  Looss. 

Fig.  10.  Rhabditiform  larva  of  Ancylostoma  duodenale  just 
hatched  from  the  egg.  After  Looss. 

Fig.  11.  Filariform  infective  larva  of  Ancylostoma  duodenale. 
After  Looss. 


PLATE  VI 


47 


48  KEY    FOR   DIAGNOSIS    OF   HUMAN    HELMINTHS 

(b)  Egg  yellowish  with  rather  thin  shell. 

Metagonimus  yokogawai  (Plate  V,  Fig.  7). 

Average  size  of  eggs  28/z  by  16/z. 

b.  Eggs  over  50/z  in  length;  do  not  contain  a  fully  devel- 
oped embryo. 

1.  Paragonimus   westermanii§.    (Plate   V,    Fig.   5). 

Size  of  egg  SO/*  to  100;u  by  52M  to  75M. 

2.  Fasciolopsis  buskii**  (Plate  V,  Fig.  1).     Size  of 

egg  120/x  to  130/z  by  77 n  to  8(V. 

3.  Gaslrodiscoides  hominis   (Gastrodiscus  hominus). 

Size  of  egg  150/z  by  72/*. 

4.  Diphyllobothrium  latum  (Dibothriocephalus  tatus) 

(Plate  V,  Fig.  12).     Size  of  egg  55/x  to  76M  by 
41/z  to  56/i,'  operculum  small  not  sharply  defined. 
Shell  thin  transparent,  light  straw  color. 
II.  Operculum  absent. 

a.    Round  or    slightly  oval,    containing    a   six-hooked 
embryo. 

1.  With  a  thick  radially  striated,  inner  shell  or  em- 

bryophore. 

(a)  Taenia  saginata   (Plate  V,   Fig.  8).     Em- 

bryophore,   ovoid,  rusty  brown,  35ju  to 
-    40/z  in  length  by  20ju  to  30ju  in  width. 

(b)  Taenia  solium  (Plate  V,  Fig.  9).     Embryo- 

phore  almost  round;  brown,  31^  to  36/i  in 
diameter. 

2.  With  thin  membranous  inner  shell. 

(a)  Hymenolepis  nana  (Plate  V,  Fig.  10).     Oval 

or  globular,  with  two  distinct  mem- 
branes; outer  3(V  to  60ju  in  diameter; 
inner  16^  to  34/z,  filiform  projections  at 
each  pole  of  inner  membrane. 

(b)  Hymenolepis   diminuta  (Plate   V,  Fig.  11) 

Round  or  oval;  outer  membrane  54ju  to 
86,u;  yellowish,  may  be  striated;  inner 
membrane  24/i  to  40/z  by  36ju. 

§  The  eggs  of  this  species  are  found  only  occasionally  in  feces  since 
in  man  they  are  usually  expelled  with  the  sputum. 

**  The  distinction  between  the  various  species  of  the  genus  Fas- 
ciolopsis described  from  man  are  so  doubtful  that  only  one  is  included 
*in  the  key. 


TREMATODA  49 

b.  Shape,  oval,  considerably  longer  than  wide. 

1.  Somewhat  barrel  shaped;  with  plugs  at  each  end. 

Trichuris  trichiura  (Plate  V,  Fig.  16).  Color 
of  eggs  dark  brown;  50/i  to  57/x  by  23ju;  ovum 
unsegmented. 

2.  Thick  transparent  shell  with  an  external  albu- 

minous coating  which  forms  protuberances. 
A  scaris  lumbricoides  (Plate  V,  Figs.  13,  14,  15). 
Color  of  eggs  brown;  50/i  to  70/*  by  40ju  to  5(V; 
ovum  unsegmented. 

3.  Asymmetrical,  flattened  on  one  side. 

(a)  Enterobius  vermicularis  (Plate  V,  Fig.  19). 

Color  transparent;  contains  tadpole  like 
embryo ;  size  of  egg  5(V  to  55/*  by  16/*  to 
24/i. 

(b)  Oxyuris  incognita  (Plate  V,  Fig.  20).     Oil 

globules  at  each  end  of  egg;  average  size 
of  egg  OOM  by  40/z. 

4.  Shell  thin,  transparent;  embryo  in  four  to  many 

cell  stages. 

(a)  Trichostrongylus  orientalis   (Plate  V,   Fig. 

21).  Ends  somewhat  pointed;  size  75/t  to 
90M  by  39M  to  47/i. 

(b)  Necator  americanus.     Size  58/x  to  SO/*  by 

35/t  to  52/z. 

(c)  Ancylostoma  duodenale  (Plate  V,  Figs.  17- 

18) .    Size  56jit  to  61/*  by  34/i  to  38/x. 

4.  TREMATODA 
A.  Definition 

Parasitic  Platyhelminthes ;  cilia  present  only  in  larval 
stage;  adults  always  covered  with  cuticula;  suckers  present 
for  attachment;  digestive  system  without  anus,  usually 
bifurcated;  development  by  metamorphosis  or  alternation 
of  generations;  adults  parasitic  in  vertebrates. 


50  INTESTINAL   TREMATODES 

B.  Systematic  Position  of  Human  Forms 

All  human  trematodes  belong  to  the  sub-class  Digenea, 
which  are  endoparasitic,  have  an  alternation  of  generations 
and  a  molluscan  intermediate  host.  Two  of  the  human 
trematodes  Gastrodiscoides  hominis  (Gastrodiscus  hominis) 
and  Watsonius  watsoni  belong  to  the  group  Amphistomata, 
which  is  characterised  by  the  presence  of  a  large  acetabulum 
at  the  posterior  end.  All  of  the  other  human  trematodes 
belong  to  the  group  Distomata,  in  which  the  acetabulum 
is  ventral  and  separated  from  the  posterior  end  by  all  or 
part  of  the  reproductive  system.  The  human  trematodes 
will  be  considered  according  to  their  position  in  the  human 
host. 

C.  Intestinal  Trematodes 

Until  recently  but  little  has  been  known  in  regard  to  the 
intestinal  trematodes  of  man.  The  two  amphistomes, 
Gastrodiscoides  (Gastrodiscus)  hominis  and  Watsonius 
watsoni,  have  been  reported  only  a  few  times  from  man, 
the  former  from  Africa  and  the  latter  from  Assam  and  India. 
Their  structure  has  been  carefully  worked  out,  but  nothing 
is  known  of  their  life  histories  and  method  of  entrance  into 
man.  Three  echinostomes,  i.e.,  distomes  with  a  circumoral 
ring  of  prominent  spines,  have  also  been  reported  from  the 
intestine  of  man.  Of  these  species  Echinostoma  ilocanum 
was  found  in  the  Philippine  'Islands,  Euparyphium  malay- 
anum  (Echinostoma  malayanum)  in  the  Malay  States  and 
Artyfechinostomum  sufrartyfex  in  India.  These  last  two 
forms  may  belong  to  the  same  species.  Three  other  intes- 
tinal flukes  of  man  Fasciolopsis  buskii,  Heterophyes  hetero- 
phyes  and  Metagonimus  yokogawai  are  of  sufficient  impor- 
tance to  require  further  description. 


INTESTINAL   TREMATODES  51 

1.  Fasciolopsis   buskii.     Large   thick   brown   trematode; 
length  24  mm.  to  70  mm.  breadth  5.5  mm.  to  14  mm.;  no 
cephalic   cone  present;  intestinal  ceca  unbranched;  ovary 
and  testes  greatly  branched;  acetabulum  larger  than  oral 
sucker,   near  anterior  end;  genital  pore  just  in  front  of 
acetabulum;  cirrus  sac  very  long,  about  one-fourth  body 
length;  intestine  of  pig  and  man;  life  history  and  method  of 
entrance  into  man  unknown;  produces  intestinal  disturb- 
ances; reported  from  India,  Siam,  China,  Cochin  China, 
Assam,  Sumatra;  common  in  some  regions  in  man  and  pig. 

Four  other  species  of  this  genus,  Fasciolopsis  rathouisi, 
goddardi,  fulleborni  and  spinifera,  have  been  reported  from 
man  by  various  authors.  They  have  been  separated  on 
minor  structural  differences  and  the  true  number  of  distinct 
species  is  still  in  doubt. 

2.  Heterophyes    heterophyes.    Very    small,    pear-shaped; 
length  up  to  2  mm.  breadth  0.4  mm.  to  1  mm.;  body  covered 
with  tiny  serrate  scales;  acetabulum  much  larger  than  oral 
sucker;  genital  pore  just  behind  the  acetabulum,  to  the  side 
and  surrounded  by  a  very  characteristic  annular  muscular 
elevation,  provided  with  75  to  80  branched  chitinous  hooks; 
habitat  small  intestine;  life  history  and  method  of  entrance 
into  man  unknown;  pathogenicity  probably  nil;  reported 
in  man  from  Egypt,  Japan  and  China,  from  dogs  and  cats 
in  Egypt,  Japan  and  Formosa. 

Another  species  of  this  genus,  Heterophyes  nocens  has  been 
described  in  man  from  Japan.  This  form  is  smaller  than 
H.  heterophyes  and  differs  in  structural  details.  The  en- 
cysted stage  is  found  in  fish,  man  being  infected  from  eating 
raw  or  imperfectly  cooked  fish. 

Si  Metagonimus  yokogawai.  Very  small  form;  length  1.5 
mm.  to  2.5  mm.,  width  0.4  mm.  to  0.7  mm.;  surface  of  body 
covered  with  nail  shaped  spines,  about  10/i  in  length; 
acetabulum  sac-like,  placed  deeply  in  the  body  and  opening 


52  LIVER    FLUKES 

dextro-laterally;  genital  pore  opens  into  a  genital  sinus  which 
opens  into  a  pit  in  front  of  the  ventral  sucker;  the  openings 
of  the  genital  sinus  and  of  the  ventral  sucker  are  furnished 
with  complex  muscular  apparatus;  found  usually  in  upper 
or  middle  portion  of  jejunum,  rarely  in  caecum;  cercaria 
develops  in  redia  in  fresh  water  snail,  Melania  libertina; 
encysted  stage  in  muscles  of  fish,  especially  trout,  Pleco- 
glossus  altivelus;  man  infected  by  eating  uncooked  fish  con- 
taining larvae;  may  cause  chronic  intestinal  catarrh  and 
frequently  destroys  intestinal  glands ;  found  in  Japan,  Korea, 
Formosa  and  China  in  man,  dog  and  cat. 

D.  Liver  Flukes 

The  large  sheep  liver  fluke,  Fasciola  hepatica,  a  closely 
related  species  F.  gigantica  and  the  lancet  fluke  of  sheep, 
Dicrocoelium  dendriticum  have  been  reported  as  incidental 
parasites  of  man.  All  the  other  human  liver  flukes,  belong 
to  the  family  Opisthorchiidae,  the  representatives  of  which 
are  common  in  fish  eating  mammals.  The  only  species  of 
medical  importance  are  Opisthorchis  felineus,  Clonorchis 
sinensis  and  C.  endemicus.  Some  authors  consider  that  the 
last  two  forms  represent  but  one  species.  In  this  outline 
they  will  be  considered,  as  separate  species.  Opisthorchis 
viverrini,  a  common  parasite  of  the  Indian  civet  cat,  has 
been  reported  incidentally  in  man  from  Chiengmai,  Siam. 
Another  species,  Amphimerus  noverca,  has  been  found  once 
in  man  in  Calcutta,  India. 

1.  Genus  Clonorchis.  Medium  'sized  flukes;  anterior 
extremity  somewhat  pointed;  body  thin  and  transparent; 
cuticula  smooth;  suckers  small  and  weak,  acetabulum  being 
smaller  than  oral  sucker;  testes  situated  one  behind  the  other 
at  posterior  end  and  very  much  branched;  ovary  and  seminal 
receptacle  small,  median,  just  in  front  of  testes;  coils  of 
uterus  fill  space  between  ovary,  and  acetabulum;  habitat  in 
bile  ducts  of  man,  cat,  dog,  etc. 


THE    LUNG    FLUKE 


53 


Clonorchis  sinensis  (Plate  VII, 
Fig.  1)  • 

Length,  13  mm.  to  22  mm. 

Width,  3  mm.  to  4  mm. 

Parenchyma    contains   numer- 
ous   yellowish    or    brownish 
pigment  granules 

Vitellaria  interrupted 

Eggs,  length  26/*  to  30M  by  15/x 
to  17 p.  Average  size  29/i  by 
Ufci 

Distribution,    China,    Cochin 
China,  Formosa 

Life  history  unknown,  prob- 
ably very  similar  to  that  of 
Clonorchis  endemicus 


Pathogenicity.  Produces  se- 
vere chronic  disturbances  of 
the  liver 


Clonorchis  endemicus 

Length  6  mm.  to  15  mm.. 
Width  1.8  mm.  to  2.6  mm. 
Parenchyma    contains    no 
ment. 


Pig- 


Vitellaria  continuous 

Egg.     Average  size  26/z  by  15ju 


Distribution      Japan,      Korea, 

Cochin  China 
Life  history:  Cercaria  develops 

in  redia  in  a  small  fresh  water 

snail,  Bythinia  striatula  var. 

Japonica;  encysted  stages  are 

found  in  a  number  of  species 

of  fresh  water  fish 
Pathogenicity.     The  same  as  in 

Clonorchis  sinensis 


2.  Opisthorchis  felineus.  Yellowish  red,  flat,  transparent 
fluke;  length  8  mm.  to  11  mm.,  width  1.5  mm.  to  2  mm.; 
testes  lobed,  obliquely  one  behind  the  other,  in  posterior 
fourth  of  body;  ovary  small,  slightly  lobed,  just  in  front  of 
testes;  uterus  fills  median  field  between  ovary  and  ventral 
sucker;  habitat  gall  bladder  and  bile  ducts  of  cats,  dogs, 
fox  and  man;  encysted  stage  in  fresh  water  fish;  found  in 
man  not  infrequently  in  Russia,  Siberia  and  East  Prussia. 
Pathogenicity  similar  to  that  of  Clonorchis  sinensis. 

E.  The  Lung  Fluke 

A  single  species  of  trematode,  Paragonimus  westermanii, 
is  found  in  the  lungs  of  man;  a  closely  related  species  Para- 
gonimus kellicotti  from  the  lungs  of  the  pig  and  cat  have 
also  been  described  from  the  United  States. 


54 


THE    BLOOD    FLUKES 


5 II  1 

OJ   -^     ?  ft    H 

I  e  S  s  j§ 

a  §  g  a  | 


1| 


j»  oo 

"a 


s 


W 


•^  -73  03 
O  "'^ 
O  '"S  ^ 
0»  C  .3 
°  ^-g 


-a 
a 


SrM  hf) 

02  Sn 

a  M  « 

..  s  2  § 

o    t     ^  o 
r~3  ^^  » — \ 


s  a  M  * 

o3  t»  **-" 

t!  ^  s  ° 

*-"  O)      " 

•2  I  'S  S 

es  ^  >  w 


J-s 

<u    fl 

-M     O 


|         o 

'S 


•a  .a      > 


So    ^ 
>•  ^ 

S.S'5 

^^  I 


. 
«  02  pq      HH 


g 

o     w 


THE    BLOOD    FLUKES 


55 


•5     o  03 

«    e        I 

81    6 


wo          M 

e  o  * 

n  s  & 

&.$  §  ^ 

'XS  O 


o 


O 


PLATE  VII 


PLATE  VII 

Fig.  1.  Adult  of  Clonorchis  sinensis.  From  Kobayashi.  Letters 
used:  c,  cirrus  sac;  eb,  excretory  bladder;  ic,  intestinal  cecum;  os, 
oral  sucker;  ov,  ovary;  ph.  pharynx;  sr,  seminal  receptacle;  t,  testis; 
u,  uterus;  vs,  ventral  sucker;  vit,  vitellaria. 

Fig.  2.  Adult  male  and  female  of  Schistosomajaponicum  in  copula. 
After  Looss. 

Fig.  3.  Scolices  and  ripe  proglottids  of  cestodes;  a,  scolex  of 
Taenia  saginata;  b,  ripe  proglottid  of  T.  saginata;  c,  Scolex  of  T. 
solium;  d,  ripe  proglottid  of  T.  solium;  e,  scolex  of  Diphyllobothrium 
latum  (Dibithriocephalus  latus};  f,  proglottids  of  D.  latum.  From 
Hertwig  after  Leuckart,  Braun,  and  Schauinsland. 

Fig.  4.  Mature  proglottid  of  Taenia  saginata.  After  Sommer. 
Letters  used:  c,  cirrus  sac;  ov,  ovary;  t,  testes;  u,  uterus;  v,  vagina, 
vit,  vitellarium. 

56 


CESTODA.      GENERAL   DISCUSSION  57 

Paragonimus  westermanii.  Color  faint  reddish  brown; 
shape  plump,  oval  like  a  coffee  grain;  length  7.5  mm.  to 
12  mm.,  width  4  mm.  to  6  mm.;  thickness  3.5  mm.  to  5 
mm.;  cuticula  covered  with  spines;  acetabulum  slightly 
larger  than  oral  sucker,  just  in  front  of  the  middle  of  the 
body;  genital  pore,  just  behind  acetabulum;  habitat  lungs, 
pleura  or  bronchi  of  man,-  dog  and  cat;  cercaria  develops 
species  of  Melania  a  common  fresh  water  snail  in  Japan; 
encysted  stage  in  land  crab  or  cray-fish;  man  infected  by 
eating  raw  crab  containing  cysts;  produces  severe  pulmonary 
disturbances  which  are  often  complicated  with  tuberculosis; 
found  in  man  in  Japan,  China,  Korea,  Formosa  and  Philip- 
pine Islands. 

F.  Blood  Flukes 

Genus  Schistosoma.  Sexes  separate;  female  elongate, 
enclosed  in  gynaecophoric  canal  of  male  at  copulation;  no 
pharynx  present;  intestinal  ceca  unite  into  a  single  median 
stem  in  posterior  part  of  body;  cercaria  forked-tailed,  devel- 
ops in  sporocysts  in  fresh  water  snail,  and  penetrates  directly 
through  the  skin  of  the  human  host;  three  species  have  been 
described  from  man,  i.e.,  Schistosoma  haematobium  S. 
mansoni  and  S.  japonicum  (Plate  VII,  Fig.  2) .  (See  page  54.) 

5.  CESTODA 
A.  Definition 

Cestodes  or  tapeworms,  ribbon  shaped  flat  worms,  divided 
into  segments  called  proglottids;  organ  of  attachment  a 
scolex  with  suckers  or  hooks;  no  digestive  tract  present. 
The  human  cestodes  fall  into  two  different  orders;  i.e.,  the 
Pseudophyllidea  and  the  Cyclophyllidea. 


58  DIPHYLLOBOTHRIUM   LATUM 

B.  Order  Pseudophyllidea 

Cestodes  with  one  or  two  groove  like  suckers  on  the  scolex; 
without  proboscis  or  rostellum;  vitellaria  are  numerous  and 
follicular;  a  uterine  pore  present;  reproductive  organs  do 
not  atrophy  as  the  uterus  develops;  whole  segments  are  not 
given  off  when  ripe  as  in  the  members  of  the  other  group; 
eggs  oval  with  operculum;  onchosphere  surrounded  by 
ciliated  membrane. 

Diphyllobothrium  latum  (Dibothriocephalus  latus)  is  the 
most  important  human  tapeworm  of  this  group.  Three 
other  species  of  the  Pseudophyllidea,  D.  cordatus,  D.  parvus 
and  Diplogonoporus  grandis,  which  are  probably  only  inci- 
dental in  man  have  been  described.  Three  larval  forms 
of  this  group  (plerocercoids)  Sparganum  mansoni,  Sparganum 
baxteri  and  Sparganum  proliferum  have  been  reported  from 
the  tissues  of  man. 

Diphyllobothrium  latum  (Dibothriocephalus  latus),  (Plate 
VII,  Fig.  3  e,  /),  or  the  fish  tape  worm.  Length  2  to  9 
meters;  3,000  to  4,200  proglottids;  scolex  almond-shaped, 
2  mm.  to  3  mm.  in  length  with  two  deep  suctorial  grooves; 
proglottids  except  in  posterior  third  of  strobila  broader 
than  long;  vagina  and  cirrus  open  close  together  on  mid- 
ventral  surface;  uterine  pore  just  behind  other  genital  pores; 
eggs  given  off  constantly  after  maturity  and  not  stored  in 
the  uterus;  ciliated  larva  from  egg  swims  freely  in  water  and 
invades  a  small  crustacean — Cyclops — developing  into  a 
procercoid ;  further  development  into  plerocercoid  in  muscles 
of  fresh-water  fish;  man  gets  infestation  by  ingesting  plero- 
cercoid from  raw  or  partly  cooked  fish;  adult  lives  in  the 
intestine  of  cat,  dog,  fox  and  man;  sometimes  produces 
severe  anaemia;  centers  of  distribution  are  French  Switzer- 
land, and  the  Baltic  Provinces  of  Russia;  found  also  in 
Italy,  Scandinavia,  Finland,  Turkestan,  Japan,  Africa, 
Madagascar  and  North  America. 


GENUS   HYMENOLEPIS  59 

C.  Order  Cyclophyllidea 

Scolex  with  four  cup  or  saucer-shaped  suckers  and  in  the 
center  an  apical  organ  or  rostellum  of  varied  form;  no 
uterine  pore;  vitellaria  compact,  single  near  posterior  end 
of  proglottid;  proglottids  set  free  after  maturity;  eggs  thin 
shelled  with  no  operculum,  contain  onchosphere  with  one 
or  more  membranes. 

General  discussion.  The  order  Cyclophyllidea  contains 
most  of  the  human  tapeworms.  Of  this  group  Hymenolepis 
nana,  H.  diminuta,  Taenia  solium,  T.  saginata  and  Echino- 
coccus  granulosus  (T.  echinococcus)  are  of  sufficient  impor- 
tance to  be  described  more  fully.  Other  forms  which  are 
incidental  in  man  or  insufficiently  knawn  are  Dipylidium 
caninum,  a  common  dog  tapeworm.  Hymenolepis  lanceolata, 
Davainea  madagascariensis,  Davainea  asiatica,  Taenia  afri- 
cana,  Taenia  hominis,  T.  confusa,  and  T.  bremneri.  It  is 
doubtful  if  all  the  forms  reported  from  man  belonging  to  the 
genus  Taenia  are  distinct  species;  they  may  simply  represent 
abnormalities  of  one  of  the  two  common  species. 

1.  Genus  Hymenolepis.  Small  worms;  proglottids  always 
broader  than  long;  three  large  testes  in  each  proglottid; 
genital  pores  unilateral,  uterus  persistent,  sac-like;  eggs 
round  or  oval  with  two  or  three  distinct  envelopes. 

H.  nana  H.  diminuta 

Length  10  to  45  mm.  Length  20  to  60  cm. 

Width  0.5  to  0.7  mm.  Width  up  to  3.5  mm. 

Scolex  globular  0.25  to  0.30  mm.  Scolex  0.2  to  0.5  mm.  in  diame- 

in  diameter  ter 

Rostellum  with  a  single  circlet  Rostellum     rudimentary     and 

of  24  to  30  hooks,  14^  to  18/z  unarmed 

in  length 

Proglottis  up  to  two  hundred  Proglottis  600-1000 

in  number 

Infection  direct  without  inter-  Larval  stage  a  small  cysticercoid 

mediate  hosts  found  in  insects 


60  ECHINOCOCCUS  GRANULOSUS 

Common  in  man;  of  cosmopoli-        Common  in  rats  and  incidental 
tan  distribution.    May  pro-  in  man 

duce   intestinal   disturbances 
especially  in  children 

2.  Genus  Taenia.  Suckers  unarmed;  uterus  with  median 
longitudinal  stem  and  lateral  branches;  female  genitalia  in 
posterior  end  of  proglottid;  genital  pores  irregularly  alter- 
nating; testes  numerous,  in  front  of  female  genitalia;  ovary 
with  two  wings;  vitellaria  behind  ovary.  Eggs  with  thin 
outer  membrane  and  striated  thick  brown  inner  shell. 
Adults  in  carnivorous  mammals  and  larval  stages  in  herbivor- 
ous mammals.  Cosmopolitan  in  distribution. 

Taenia  solium  (Plate  VII,  Taenia  saginata  (Plate  VII, 

Fig.  3  c,  d)  Fig.  4  and  3  a,  b) 

Scolex  globular  about  1  mm.  in  Scolex   quadrangular   1.5    to   2 

length  mm. 

Rosellum  with  two   crowns  of  Rostellum  and  hooks  absent 

hooks 

Length  2-8  meters  Length  4-12  meters 

Number  of  proglottids  700-1000  Number  of  proglottids  about  2000 

Genital  pores  irregularly  alter-  Genital    pores    more    regularly 

nating  alternating 

Branches   of   uterus   in   gravid  Branches   of   uterus   in   gravid 

proglottis  5  to  10  in  number  proglottis  15-30,  dichotomous 

and  dendritic 

Proglottids  expelled  in  groups  Proglottids  expelled  singly  and 

passively  with  feces  may  force  anal  sphincter 

Larval  form  Cysticercus    cellu-  Larval   form   Cysticercus    bovis 

losae    of    the  pig,   sometimes  in  cattle,  never  found  in  man 

in  man 

8.  Echinococcus  granulosus  (Taenia  echinococcus).  Adult 
inhabits  small  intestine  of  dog,  jackall  and  wolf;  measures 
2.5  to  6  mm.  in  length;  scolex  0.3  mm.  in  breadth  with  a 
double  row  of  twenty-eight  to  fifty  booklets  on  the  rostellum ; 
number  of  segments  3  to  4,  the  posterior  segment  being  about 


PLATE  V1I1 


PLATE  VIII 

Fig.  1.  Anterior  end  of  Necator  americanus.    From  Looss. 

Fig.  2.  Anterior  end  of  Ancylostoma  duodenale.    From  Looss. 

Fig.  3.  Bursa  of  Necator  americanus.    From  Looss. 

Fig.  4.  Bursa  of  Ancylostoma  duodenale.    From  Looss. 

Fig.  5.  Adult  male  of  Enter obius  vermicularis  (Oxyuris  vermicu- 
laris).  From  Leuckart. 

Fig.  6.  Adult  female  of  Enterobius  vermicularis  (Oxyuris  vermi- 
cularis). From  Leuckart.  Letters  used:  a,  anus;  es,  esophagus; 
i,  intestine;  ov,  ovary;  u,  uterus;  v,  vulva;  vg,  vagina. 

Fig.  7.  Adult  male  of  Trichuris  trichiura.  From  Castellani  and 
Chalmers  after  Glaus.  Letters  used:  s,  spicule;  sv,  seminal  vesicle; 
t,  testis. 

Fig.  8.  Adult  female  of  Trichuris  trichiura.  From  Castellani  and 
Chalmers  after  Glaus. 

61 


62  NEMATODA.    FAMILY   ANGIOSTOMIDAE 

2  mm.  in  length  and  0.5  mm.  in  width.  Larval  stage, 
Echinococcus  polymorphous  or  hydatid  of  man  which  may 
attain  the  size  of  a  child's  head ;  found  also  in  cattle,  sheep, 
pigs  and  numerous  other  species  of  mammals;  hydatid  cyst 
composed  of  outer  layer  of  striated  cuticula  and  inner 
protoplasmic  germinating  membrane  and  is  filled  with 
fluid;  daughter  cysts  may  be  formed  internally  or  externally; 
numerous  scolices  are  formed  in  brood  capsules  within  cyst ; 
over  50  per  cent  of  hydatids  in  man  found  in  the  liver;  may 
also  develop  in  lungs,  kidneys,  cranial  cavity,  genitalia, 
organs  of  circulation,  'spleen,  etc. ;  growth  of  cyst  produces 
symptoms  depending  on  organ  involved;  found  whenever 
man  is  closely  associated  with  dogs,  especially  in  cattle  or 
sheep  raising  countries;  especially  prevalent  in  Iceland  and 
Australia. 

Possibly  Echinococcus  multilocularis  a  type  of  hydatid 
found  especially  in  Russia,  Germany  and  Switzerland,  should 
be  considered  as  a  separate  species. 

6.  NEMATODA 

A.  Definition 

Nematodes  or  round  worms,  bilaterally  symmetrical^ 
unsegmented;  digestive  system  with  both  mouth  and  anus; 
no  true  coelom  but  a  large  body  cavity  is  present  between 
the  body  wall  and  digestive  tract;  sexes  separate;  body 
covered  with  thick  cuticula;  reproductive  organs  simple 
tubular.  The  nematodes  will  be  taken  up  according  to  the 
families  which  have  human  representatives. 

B.  Family  Angiostomidae 

Small  nematodes;  characterized  by  heterogeny;  each 
species  having  a  parasitic  filariform  generation  alternating 
with  a  bisexual,  free-living,  rhabditiform  generation. 


THE    GUINEA   WORM  63 

• 

Strongyloides  stercoralis.  Parasitic  female  (Plate  VI,  Fig. 
5),  length  about  2.2  mm.;  width  0.037  mm.  to  0.07  mm.; 
cuticula  with  fine  transverse  striations;  mouth  surrounded 
by  four  lips;  esophagus  cylindrical,  filariform,  one-third 
body  length;  anus  just  in  front  of  pointed  posterior  extrem- 
ity; vulva  at  posterior  limit  of  middle  third  of  body;  eggs 
50ju  to  58/-1  in  length  and  30ju  to  34/z  in  width;  usually  lie  in 
chain  and  hatch  in  small  intestine  into  rhabditiform  larvae 
(Plate  VI,  Fig.  8) ;  eggs  probably  produced  by  parthenogenesis ; 
rhabditiform  larvae  develop  at  high  temperature  (26°  to 
35°C.)  in  about  30  hours  into  free  living  rhabditiform 
generation  of  males  and  females  (Plate  VI,  Figs.  6  and  7); 
these  produce  eggs  about  70ju  by  45ju  which  hatch  into  a  new 
generation  of  rhabditiform  larvae;  these  larvae  grow  in  about 
eight  days  into  the  filariform  infective  larva  (Plate  VI, 
Fig.  9) ;  infects  man  through  the  skin  or  mouth  and  develops 
into  the  parasitic  filariform  female  in  small  intestine;  at 
lower  external  temperature  the  free,  living  generation  may 
be  omitted  and  infective  larvae  develop  from  first  brood 
of  rhabditiform  larvae;  when  present  in  large  numbers 
produces  intestinal  catarrh  leading  to  anaemia  and  intermit- 
tant  diarrhoea;  found  everywhere  in  tropics  and  sub-tropics 
where  there  is  sufficient  moisture  for  development  of  larvae; 
distribution  coincides  with  that  of  hookworm  but  incidence 
much  less. 

C.  Family  Dracunculidae 

Long  threadlike  nematodes;  male  very  small  in  proportion 
to  female;  anus  absent;  ovo viviparous;  aquatic  crustacean 
intermediate  host  necessary  for  development. 

Dracunculus  medinensis  or  the  guinea  worm.  Females, 
length  50  cm.  to  80  cm.,  width  1.5  mm.  to  1.7  mm.;  color 
whitish  or  yellowish;  anterior  extremity  rounded  and  bears 
a  cuticular  thickening  or  shield;  alimentary  canal  below 


-64  THE    FILABIDAE 

• 

esophagus  atrophied;  anus  absent;  long  uterus  containing 
large  numbers  of  free  embryos  fills  most  of  body;  vulva 
near  anterior  end;  male  very  poorly  known;  adult  female 
in  subcutaneous  tissue  of  host,  producing  superficial  ulcers 
through  which  embryos  are  extruded;  larvae  enter  small 
crustacean,  cyclops,  in  water  and  reach  man  through  inges- 
tion  of  cyclops;  distribution,  Africa,  Arabia,  Persia,  Turke- 
stan, Hindustan,  Fiji  Islands;  imported  to  South  America, 
but  only  present  in  a  few  places. 

D.  Family  Filaridae 

Long  thread  like  nematodes;  anus  present;  esophagus 
without  bulb;  vulva  in  anterior  half  of  body;  two  ovaries; 
generally  ovo viviparous;  development  requires  a  blood- 
sucking insect  as  intermediate  host. 

General  discussion.  A  large  numb'er  of  different  forms 
have  been  described  from  man  as  belonging  to  this  family. 
Some  are  known  only  in  the  microfilaria  stage  and  some  in  an 
immature  stage  to  which  the  name  agamofilaria  is  given.  A 
discussion  will  be  given  here  only  of  those  species  which  are 
known  in  the  adult  stage,  and  for  which  the  specific  identity 
seems  to  be  certain. 

1.  Filaria  bancrofti.  Worms  whitish,  long,  filiform,  cuti- 
cula  smooth;  head  globular,  terminating  in  a  simple,  circular, 
unarmed,  lipless  mouth,  tail  rounded.  Male,  length  25 
mm.  to  38  mm.  width  0.12  mm.;  tail  curved  or  spiral;  anus 
0.13  mm.  from  posterior  end;  guarded  by  two  projecting 
lips;  two  unequal  curved  retractile  spicules,  larger,  0.6  mm. 
and  smaller,  0.2  mm.  in  length.  Female,  length  76  mm. 
to  100  mm.,  thickness  0.18  mm.  to  0.28  mm.;  vulva  about 
1.2  mm.  from  anterior  end.  Adults  live  in  lymphatic  glands, 
larvae  (Plate  VI,  Fig.  3)  in  blood,  appearing  in  peripheral 
blood  at  night;  intermediate  hosts  various  species  of  mos- 


THE    FILARIDAE  65 

quitoes;  produces  disturbances  of  the  lymphatic  system 
and  is  related  to  elephantiasis;  common  in  Asia,  Oceania, 
West  Indies,  Central  and  Tropical  South  America,  Africa; 
one  endemic  center  in  Charleston,  South  Carolina,  U.  S.  A. 

2.  Filaria   ozzardi    (Filaria   demarquayi).     Female    only, 
known;  length  65  mm.  to  80  mm.;  width  0.21  mm.  to  0.25 
mm.;  vulva  0.76  mm.  from  anterior  tip;  head  has  diameter 
of  0.1  mm.;  anus  0.25  mm.  from  posterior  end;  tail  with  a 
pair  of  characteristic  fleshy  papillae  at  tip;  adults  live  in 
connective  tissue;  effect  on  host  probably  nil;  distribution, 
St.  Vincent,  Dominica,  Trinidad,  St.  Lucia,  British  Guiana. 

3.  Loa  loa  (Filaria  loo).     Cuticula  with  scattered,  rounded 
thickenings  or  bosses;  male  thin,  white  almost  transparent, 
with  body  tapering  to  each  extremity;  length  25  mm.  to 
34  mm.;  width  0.27  mm.  to  0.43  mm.;  head  like  truncated 
cone;  tail  somewhat  incurved  with  rounded  tip;  anus  0.075 
mm.  to  0.082  mm.  from  tip  of  tail;  three  pairs  of  well  marked 
preanal  papillae  and  two  pairs  of  post-anal  papillae  present; 
spicules  unequal  0.113  mm.  and  0.176  mm.  long;  female, 
length  45  mm.  to  63  mm.;  width  0.5  mm.;  vulva  situated 
about  2  mm.  from  the  anterior  end;  adult  in  superficial 
connective  tissue — the  conjunctiva,  the  subcutaneous  fat,  the 
superficial  aponeuroses  in  all  parts  of  the  body;  larvae 
(Plate  VI,  Fig.  2)  only  found  in  peripheral  blood  during  the 
day;  development  of  larvae  takes  place  in  salivary  glands 
of  a  mango-fly  (Crysops  dimidiatus) ;  almost  entirely  limited 
to  Africa;  especially  West  Coast. 

4-  Acanthocheilonoma  perstans  (Filaria  perstans).  Body 
cylindrical,  uniform,  except  toward  both  ends  where  it 
tapers  a  little.  Male,  rarely  met  with;  length  45  mm. 
width  0.6  mm.  to  0.8  mm.;  tail  greatly  curved  ending  in  a 
bifid  prolongation  of  cuticula;  spicules  very  unequal  in  size; 
four  pairs  of  pre-anal  and  two  pairs  of  post-anal  papillae 
present.  Female  70  mm.  to  80  mm.  in  length;  width  0.12 


66  THE    FILARIDAE 

mm.;  head  rounded,  neck  long;  alimentary  canal  not  differ- 
entiated into  esophagus  and  intestine;  anus  opens  on  a 
papilla  0.145  mm.  in  front  of  posterior  tip;  vulva  0.6  mm. 
from  anterior  extremity;  uterus  double  and  when  full  of 
eggs  and  embryos  nearly  fills  body;  adults  found  free  in 
connective  tissue  at  the  base  of  the  mesentery  around  the 
pancreas,  behind  the  pericardium,  and  behind  the  abdominal 
aorta  and  suprarenal  capsules;  microfilariae  (Plate  VI, 
Fig.  4)  in  peripheral  blood  show  no  periodicity;  life  history 
unknown;  effect  on  host  apparently  nil;  found  in  tropical 
Africa  and  British  Guiana. 

5.  Dirofilaria     magalhaesi.     Worms     white,     opalescent, 
transversely  striated;  head   club-shaped  and  simple;  eso- 
phagus with  a  bulb;  tail  rounded.     Male,  length  83  mm. 
width  0.28  mm.  to  0.4  mm.;  cloaca  D.ll  mm.  from  posterior 
tip;  two  unequal  spicules;  four  pre-anal  and  three  post-anal 
pairs  of  papillae.    Female,  length  155  mm.;  width  0.6  mm., 
to  0.8  mm.;  vulva  2.56  mm.  behind  anterior  tip;  anus  0.13 
mm.  in  front  of  tip  of  tail.;  lives  in  heart;  life  history  and 
pathogenicity  unknown;  found  in  Brazil. 

6.  Onchocerca    volvulus.     Body    white    filiform,    slightly 
attenuated  at  the  ends;  cuticula  transversely  striated;  head 
rounded;  mouth  unarmed;  alimentary  canal  straight  and 
un differentiated.     Male,  length  30  mm.  to  35  mm.;  width 
0.14  mm.;  tail  strongly  recurved  and  somewhat  flattened  on 
its  concave  aspect;  three  pairs  of  papillae  present  on  each 
side  of  the  anus;  three  pairs  of  post-anal  papillae;  two 
unequal  spicules  the  larger  measuring  0.077  mm.  and  the 
smaller  0.082  mm.  in  length;  female,  length  60  mm.  to  70 
mm.;  width  0.36  mm.;  cuticular  striations  ring  like  and  well 
marked;  tail  recurved;  vulva  0.76  mm.  from  the  anterior 
end;  found  in  sub-cutaneous  tumors  from  the  size  of  a  pea 
to  that  of  a  pigeons  egg;  usually  found  in  axilla,  popliteal 
space,  about  the  elbow,  in  the  sub-occipital  region  and  in 


THE    TRICHINELLIDAE  67 

the  intercostal  spaces;  produce  lymphangitis  and  peri- 
lymphangitis  which  is  sometimes  acute,  with  fever;  embryos 
found  in  lymph  spaces  around  the  adult  worms;  life  history 
unknown;  found  in  tropical  Africa. 

A  new  species  Onchocerca  caecutiens  has  recently  been 
reported  from  Guatemala;  this  form  is  distinguished  with 
difficulty,  morphologically,  from  O.  volvulus;  it  produces 
tumors  and  an  erysipelas  like  condition  of  the  head  and  neck. 

E.  Family  Trichinellidae 

Esophagus,  a  chain  of  single  cells  with  intracellular  lumen; 
body  divided  into  attenuated  anterior  region  and  thicker 
posterior  region,  containing  the  reproductive  organs;  ovary 
single,  vulva  at  junction  of  anterior  and  posterior  regions. 

I.-  Trichuris  trichiura  (Plate  VIII,  Figs.  7  and  8)  or  the 
whipworm.  Anterior  region  of  the  body  very  long  and 
thread  like;  the  posterior  thicker  portion  truncated  with  a 
terminal  anus;  male,  with  a  spirally  rolled  posterior  end; 
length  40  mm.  to  45  mm.;  single  spicule,  which  lies  in  a 
retractile  pouch  beset  with  spines,  25  mm.  long;  female, 
length  45  mm.  to  50  mm.;  thicker  posterior  region  equals 
two-fifths  of  body  length;  lives  in  caecum  and  sometimes  in 
the  vermiform  appendix,  with  its  anterior  end  buried  in 
mucous  membrane;  infection  direct;  larvae  within  the  egg 
require  a  long  period  outside  of  body  for  development; 
usually  apparently  harmless,  but  at  times  may  give  rise  to 
anemia  and  intestinal  disturbances,  and  occasionally  appen- 
dicitis; distribution  cosmopolitan. 

2.  Trichinelia  spiralis  (Trichina  spiralis).  Male,  length 
1.4  mm.  to  1.6  mm.;  .width  0.4  mm.;  anterior  region  of  body 
narrowed;  orifice  of  cloaca  terminal  and  lies  between  two 
caudal  appendages;  internal  to  these  are  two  pairs  of  papillae, 
the  dorsal  one  behind  the  other;  female,  length  3  mm.  to 


DO  THE   TKICHOSTRONGYLIDAE 

4  mm.;  width  0.06  mm.;  anus  terminal;  vulva  in  anterior 
region;  lives  in  adult  stage  in  small  intestine  of  man,  pig, 
wild  boar  and  rat;  experimentally  it  may  be  introduced 
into  almost  any  mammal;  larvae  becomes  encysted  in 
muscles  of  same  host  as  adult;  man  gains  infection  by  eating 
raw  or  partly  cooked  pork  containing  these  encysted  larvae; 
produces  disease  known  as  trichinosis  which  is  very  severe 
when  infection  is  heavy;  found  everywhere  that  man  eats 
pork. 

F.  Family  Metastrongylidae 

Bursa  in  male  with  true  but  rather  stunted  rays;  buccal 
capsule  absent  or  slightly  developed;  vagina  elongate; 
uteri  convergent;  parasitic  in  the  respiratory  or  circulatory 
systems. 

The  only  species  of  this  family  which  has  been  reported 
from  man  is  Metastrongylus  apri,  which  is  a  common  parasite 
of  the  bronchial  tubes  of  pigs.  This  form  has  been  reported 
only  a  few  times  and  is  evidently  an  incidental  parasite  of 
man. 

G.  Family  Trichostrongylidae 

Bursa  of  male  large  with  well  developed  rays;  buccal 
capsule  absent  or  slightly  developed;  vagina  short;  uteri 
divergent;  ovejectors  differentiated;  parasitic  in  alimentary 
canal. 

Trichostrongylus.orientalis.  Body  tapers  gradually  anter- 
iorly; head  with  three  small  lips  and  blunt  or  pointed  papil- 
lae; cuticula  transversely  striated;  esophagus  long;  male, 
length  3.8  mm.  to  4.8  mm.;  spicules  spoon  like,  with  a 
boat  shaped  accessory  piece,  0.11  mm.  to  0.13  mm.  in  length; 
bursa  closed  around  with  large  side  flaps  and  without  evident 
median  folds;  female,  length  4.9  mm.  to  6.7  mm.;  vulva 
in  posterior  half  of  body;  tail  short  with  two  small  papillae 


THE   HOOKWORMS  69 

near  the  tip;  parasite  of  the  small  intestine;  life  history 
unknown;  pathogenicity  probably  nil;  common  in  Japan. 
Three  other  species  of  this  genus,  Trichostrongylus  colubri- 
formis,  T.  probolurus  and  T.  vitrinus  which  are  common 
parasites  of  sheep  and  other  ruminants  have  been  reported 
incidentally  from  man.  These  forms  are  easily  overlooked 
since  the  adults  are  very  small  and  the  eggs  resemble  hook- 
worm eggs.  It  is  therefore  possible  that  members  of  this 
genus  are  more  common  in  man  than  is  at  present  reported. 
Two  other  species  belonging  to  this  family,  Haemonchus 
contortus  and  Mecistocirrus  fordi  (Nematodirus  gibsoni) 
which  are  common  parasites  of  domestic  animals,  have  been 
reported  incidentally  from  man. 

H.  Family  Ancylostomidae 

Bursa  large  with  well  defined  rays;  buccal  capsule  well 
developed;  uteri  divergent;  parasites  of  alimentary  canal. 

1.  Sub-family  Ancylostominae.  Buccal  capsule  funnel- 
shaped,  provided  on  ventral  side  with  hooks  or  teeth;  bursa 
of  male  closed  all  around;  only  one-third  of  dorsal  ray 
cleft;  course  of  genital  tubes  longitudinal. 

Ancylostoma  duodenale  (Plate  VIII,  Figs.  2  and  4).  Body 
cylindrical;  tapering  anteriorly;  flesh  colored  when  alive; 
cuticula  ringed;  buccal  capsule  carries  ventrally  two  pairs 
of  hooklike  teeth;  male,  length,  about  10  mm.;  width  0.4 
mm.  to  0.5  mm.;  bursa  umbrella  shaped;  rays  shown  in 
figure;  two  slender  spicules,  about  2  mm.  long  without 
barbs;  female  12  mm.  to  13  mm.  in  length;  vulva  behind 
middle  of  body;  adults  live  in  small  intestine;  eggs  hatch 
outside  body  into  rhabditiform  larvae;  grow  in  4  to  6  days 
into  the  filariform  infective  larvae,  which  enter  man  through 
skin  or  by  way  of  the  mouth;  frequently  produces  a  serious 
disease,  characterized  by  intestinal  disturbances  and  anemia; 


70  THE   HOOKWORMS 

distribution  world  wide,  in  tropical  and  subtropical  regions, 
where  there  is  sufficient  moisture  for  the  development  of  the 
larval  stages. 

Two  other  species  of  this  genus  have  been  reported  from 
man,  Ancylostoma  ceylonicun  from  India  and  Ancylostoma 
braziliense  from  Brazil.  Some  authorities  think  that  these 
two  forms  belong  to  the  same  species.  They  are  common 
parasites  of  the  cat  and  civet  cat  and  probably  only  inci- 
dental in  man. 

2.  Suit-family  Bunostominae.  Small  buccal  capsule,  with 
aperture  narrowed  anteriorly  by  plates  with  cutting  edges 
springing  from  the  sides,  and  more  or  less  covering  the 
ventral  half  of  the  aperture;  coils  of  genital  tubes  very 
numerous  and  close.  Externo-dorsal  ray  thin  more  espe- 
cially at  the  root;  spicules  of  the  male  barbed  at  ends. 

Necator  americanus  (Plate  VIII,  Figs.  1  and  3).  Head 
bent,  strongly  dorsally,  small  buccal  capsule  armed  only  with 
semilunar"  plates:  male,  7  mm.  to  9  mm.  in  length  and  0.3 
mrn.  to  0.35  mm.  in  width;  bursa  shown  in  figure;  spicules 
long  and  slender,  0.92  mm.  in  length  and  terminate  in 
barbed  points;  female  9  mm.  to  12.6  mm.  in  length;  vulva 
just  in  front  of  middle  of  body;  position  in  host  and  life 
history  as  in  Ancylostoma  duodenale. 

I.  Family  Strongylidae 

Cylindroid  rarely  filiform  bodies;  mouth  usually  with 
wide  buccal  capsule  and  a  ring  of  chitinous  armature; 
esophagus  more  or  less  enlarged  posteriorly;  male  with  bursa 
and  two  equal  spicules;  females  with  two  ovaries;  vulva 
situated  medially  or  posteriorly;  species  as  rule  small. 

Termidens  diminutus,  Oesophagostomum  brumpti,  0. 
stephanostomum  var.  thomasi,  0.  apiostomum,  are  parasites  in 
the  large  intestine  of  man  and  monkeys  in  Africa  and  South 


ASCAKIS   LUMBRICOIDES  71 

America.  The  species  of  the  genus  Oesophagostomum  are 
peculiar  in  that  the  larvae  are  often  found  in  tumorous 
nodules  of  the  intestinal  wall.  The  distribution  and  pre- 
valence of  these  forms  in  man  is  still  insufficiently  known. 

J.  Family  Ascaridae 

Large  thick  nematodes;  mouth  with  three  lips,  one  dorsal 
and  two  lateral;  esophagus  with  a  bulb;  male  with  two 
spicules;  female  with  two  ovaries;  development  direct. 

A  scans  lumbricoides.  Very  large  worms;  male  measures 
15  to  25  cm.  in  length  and  about  3  mm.  in  diameter;  posterior 
end  is  conical  and  hooked  ventrally;  spicules  measure  2  mm. 
in  length  are  curved  and  somewhat  broadened  at  their  free 
end;  female  measures  20  to  40  cm.  in  length  and  about 
5  mm.  in  diameter;  posterior  extremity  conical  and  straight; 
vulva  at  junction  of  anterior  and  middle  thirds  of  the  body; 
development  of  larvae  in  egg  requires  considerable  time; 
infection  direct  without  intermediate  host  but  with  wander- 
ing of  larvae  through  the  tissues  especially  lungs  before 
they  settle  in  intestine;  may  produce  intestinal  disturbances; 
wandering  of  larvae  probably  produce  pulmonary  disturb- 
ances especially  in  children;  habitat  small  intestine;  cosmo- 
politan in  distribution. 

Two  doubtful  species,  Ascaris  texana  and  Ascaris  maritima 
have  been  described  from  man.  A  rare  form  Lagochilascaris 
minor  has  been  described  from  Trinidad,  which  is  easily 
distinguished  from  Ascaris  lumbricoides  by  the  presence 
along  the  lateral  lines  of  cuticular  wings  extending  the 
whole  length  of  the  body.  Toxascaris  limbata  from  the 
dog  and  Belascaris  cati  from  the  cat  have  been  reported  a 
few  times  from  man. 


72  ENTEEOBIUS    (OXYURIS)    VERMICULARIS 

K.  Family  Oxyuridae 

Small  to  medium  sized  forms;  cuticula  thickened  on  each 
side  for  the  whole  length  of  body  in  the  form  of  a  lateral 
flange  or  wing;  esophagus  long  with  a  well  marked  bulb 
containing  a  valvular  apparatus;  tail  end  of  female  drawn 
out  into  a  long  point;  eggs  asymmetrical;  males  much  smaller 
than  females,  with  one  spicule. 

Enterobius  vermicularis  (Oxyuris  vermicularis)  (Plate 
VIII,  Figs.  5  and  6).  Pin  worm;  color  white  with  striated 
inflation  of  the  cuticula  at  the  anterior  end;  male  3  to  5 
mm.  in  length;  posterior  extremity  of  body  is  curved  ven- 
trally  and  has  six  papillae;  single  spicule,  about  70ju  long, 
hooklike;  female,  about  10  mm.  in  length;  anus  2  mm. 
from  tip  of  much  attenuated  tail;  vulva  in  anterior  third 
of  body.  Adults  in  large  intestine  of  man;  young  forms  in 
posterior  part  of  small  intestine  and  often  appendix;  infec- 
tion direct  without  intermediate  host;  time  of  development 
of  larvae  in  eggs  required  outside  of  host  very  short;  in 
large  numbers  may  produce  enterocolitis  and  appendicitis 
small  numbers  produce  irritation;  distribution  cosmopolitan. 

An  oxyuris  like  egg  has  been  found  in  fecal  examinations 
to  which  the  name  Oxyuris  incognita  (Plate  V,  Fig.  20)  has 
been  given.  Nothing  is  known  of  the  adult  to  which  this 
egg  belongs.  Recently  Syphacia  obvelata,  a  mouse  oxyurid 
has  been  reported  incidentally  from  man. 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 
BERKELEY 


Return  to  desk  from  which  borrowed. 
This  book  is  DUE  on  the  last  date  stamped  below. 


JAN  22  1952 
JflW  22  1952 

FEB19  1964 
!8Fe'S4WG 


LD  21-95m-ll,'50(2877sl6)476 


